(With great thanks to /u/voyeur324)

In addition to the angels one, I have some answers about the history of hell and Satan--most of which, in fact, is medieval and pre-Dante!

To start, here's an answer about the history of hell that actually looks at "what is hell like" (fire, punishments, etc) leading up to Dante, who pretty much codifies what you think of today:

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Yeah, yeah, Dante always gets all the credit. Don't get me wrong--the breathtaking scope, literary dexterity, theological and political ambition of the Commedia make it a suitable and attention-grabbing reference point. But Dante's versions of hell, purgatory, and heaven are deeply rooted in more than a millennium of Christian visions of the afterlife (influenced by various pre-Christian and philosophical traditions as well). For the early Middle Ages up through 1200, in fact, visions of heaven and hell were the single most popular form of religious vision narrative in the Latin west. (They don't exactly diminish in popularity afterwards, but other forms of visions become cultural tsunamis). Don't worry; for this answer I will concentrate on hell. ;)

The Bible does give us the idea of a "lake of fire," but it's remarkably scant on other details. Nevertheless, already in the New Testament apocrypha (texts written a bit later than the canonical NT books), there are extensive visions of the afterlife in the Apocalypse of Peter and in the Shepherd of Hermas. The Apocalypse of Peter is intriguing because it already develops the idea of the contrapasso, or "the punishment symbolizes the sin."

Early medieval voyages to the afterlife often take on, as a whole, the tone of a morality tale. A newly deceased sinner is given a cosmic tour, only to come back to life to spread the message of the joys of paradise/horrors of hell (and, of course, they inevitably clean up their life). One of the innovations of this era, that Dante will also draw out, is the use of hell visions as political weapons. More often this is much vaguer than Dante, like placing all the bishops who buy and sell offices in hell. But there's a reason for that. These visions are written and passed down as experiences that "actually happened"--as genuine witnesses to the underworld.

By the high Middle Ages, there's a new wrinkle in the medieval visionary tradition: the idea that "living saints," particularly women, are specially graced by God with divine visions. Although much of the women's visionary corpus is Christocentric, many visionaries receive (or ask for and are denied, as with Julian of Norwich in the 14-15C) a short trip through heaven and/or hell. Women's visionaries of purgatory, meanwhile, often involve these living saints actually pulling people out according to God's will and then by their own prayerful and ascetic intercession. Mechthild of Hackeborn, a late 13th century German visionary whose visions of paradise sparkle with gemstones and light, is typically proposed as Dante's "Matilda"--that is, that he was familiar with her and her visionary text, the Liber specialis gratie.

But for my money, the best high medieval vision of hell belongs to Mechthild of Magdeburg, an independent religious women slightly older than her co-named monastic counterpart. Mechthild has extensive and lavishly described visions of paradise and purgatory as well, but her hell is top-notch. You can read a fair portion of Frank Tobin's translation of it on Google Books (scroll down a bit on that first page), and you absolutely should.

I have seen a city / its name is eternal hate

It was built in the deepest abyss / From all kinds of stones of huge capital sins

[...] Lucifer sits bound by his guilt in the deepest abyss. There flows unceasingly out of his fiery heart and out of his mouth all the sins, torments, sickness, and shame in which hell, purgatory, and the earth are so wretchedly entangled. In the bottommost part of hell, the fire, gloom, stench, shuddering, and all kinds of intense pain are the greatest.

[...][Lucifer] grabs the proud one and thrusts him under his tail and says: "I have not sunk so deep that I shall not lord it over you." All the sodomites pass down his throat and live in his belly. Whenever he draws a breath, they slide into his belly. But when he coughs, they are expelled again.

The false saints he puts upon his lap, kisses them hideously...Unceasingly he gnaws the usurer and rebukes him fo rhaving have been moved by mercy. The thief is strung up by the feet to serve in hell as a beacon, but the damned do not see the better for it.

[...] At the top, hell has a head that is hideous and has on it numerous fierce eyes which shoot forth flames.

Oh, Mechthild!

I introduce that last bit because there is a parallel tradition that passes down ideas of (especially) hell in the Middle Ages: art. Indeed, depictions of hell were a standard feature in church sculpture, generally as part of a Last Judgment scene. And while Dante's "gates of hell" have their place in iconography (though note that Satan's jaws have a starring role in the lowest level of hell), Mechthild's reference to hell having a head arrives at the iconographic symbol of hell up to the Reformation: the hellmouth. That's right. Long before it was terrorizing the students of Sunnydale High School, hellmouths were all over medieval manuscripts, churches, and imaginations. Sometimes they are more reptilian, sometimes more lion-like, sometimes just abstract evil with eyes.

As far as conceptions of the afterlife go, Dante's importance is less in creativity and more in sealing the deal. The insane popularity of the Commedia and its enduring hold on western imaginations means we are likely to continue to talk of hell in terms of his metaphors and descriptions. But those literary devices have deep and fertile roots.

To add some broader cross-cultural context to /u/sunagainstgold 's very interesting explanation of the literary history of Christian views of hell, visions of an afterlife split into punishment and reward have a long history in Zoroastrian tradition. The earliest definitive attestation of an individual experiencing a vision of the afterlife is from the high priest Kerdir's inscription at Naqsh-i Rajab, from around the 270's AD:

(1) I, Kartir, am known in the empire for righteousness and eminence, and known to (2) have been of good service and good will to the Yazads and lords. Further I to the Yazads ward this also (3) thus promised, that, if by the help of the Yazads I, Kartir, for the living upon (4) highest rank were made to look then also by me further to the departed ward of heaven (5) and hell the essential features would be outlined (or proclaimed or enlarged) for the sake, also, of these divine services as within the empire they are performed, for the sake of these also. (6) ...

...Now another (17) matter; not everyone may issue a command at will. Let it be known what I have decided: (18) There is a heaven and there is a hell. And whoever is a welldoer shall go straight to heaven. (19) And whoever is a sinner shall be cast down to hell. And whoever is a welldoer and after (20) welldoing persistently runs, this one (in) this bone-endowed body good fame and prosperity (21) shall attain and also (in) this bone-endowed spirit orthodoxy shall (he) overtake, (22) as I, Kartir, have attained.

(Unfortunately, I don't have a faqsimile to see exactly what has been translated "heaven" and "hell" respectively here).

The first time we get a more elaborate account is in the tale of "The Righteous Wiraz" (Arda Wiraz), which unfortunately is of indeterminate age - presumably first put to paper in the middle-late Sasanian period drawing on various earlier traditions. It narrates that

... the soul of Viraf went, from the body, to the Bridge of Reckoning of Chakat-i-Daitik, (2) and came back the seventh day, and went into the body. (3) Viraf rose up, as if he arose from a pleasant sleep, (4) thinking of Vohuman and joyful.

This is quite a long work, but it is surprisingly recognizable, for example:

I came back again to the Bridge of Reckoning. (2) And I saw a soul of those who were wicked ... 10. Afterward, a stinking cold wind comes to meet him. ... And in that wind he saw his own way of life and deeds as a profligate woman, naked, decayed, gapping, bandy-legged, lean-hipped, and unlimitedly spotted so that spot was joined to spot, like the most hideous, noxious creature, most filthy and most stinking.

Then that wicked soul spoke thus: 'Who art thou, than whom I never saw any one of the creatures of Ohrmazd and Ahriman uglier, or filthier, or more stinking?'

To him she spoke thus: 'I am thy bad actions, O youth of evil thoughts, of evil words, of evil deeds, of evil way of life. (15) It is on account of thy will and actions that I am hideous and vile, iniquitous and diseased, rotten and foul-smelling, unfortunate and distressed, as appears to thee. (16) When thou sawest any one who performed the Yazishn and Dron ceremonies, and praise and prayer and the service of God; (17) and preserved and protected water and fire, cattle and trees, and other good creations; (18) thou practicedst the will of Ahriman and the demons, and improper actions. ....'

The last paragraph goes on for quite a while more, and the rest of the work goes over a mind-boggling number of people being the victims of increasingly cruel forms of torture as punishment for their (sometimes incredibly petty) sins:

1. I also saw the souls of women, by whom their own menstrual discharge was ever devoured.

2. And I asked thus: 'What sin was committed by the body of these, whose souls suffer so severe a punishment?'

3. Srosh the pious, and Adar the angel, said (4) thus: 'These are the souls of those women who heeded not their menstruation, (5) and injured water and fire and the earth of Spandarmad and Hordad and Amurdad, (6) and looked upon the sky and the sun and the moon, (7) and injured cattle and sheep with their menstruation, (8) and kept the pious man polluted.'

In general, the idea in Zoroastrianism is that the tortures are meant to punish or purify evildoers so that they can be restored at the end times. However, this doesn't always accord well with what we see in works like Arda Wiraz - the underworld apparently abounds with xrafshtar who punish people, despite the fact that these are the creations of Ahriman. And having witnessed countless sinners, Wiraz finally comes upon Ahriman himself who is apparently engaging in a favourite pastime:

1. Then I saw Ahriman, the deadly, the world-destroyer, whose way of life is evil, (2) who ever ridiculed and mocked the wicked in hell, and said (3) thus: 'Why did you ever eat the bread of Ohrmazd, and do my work? (4) and thought not of your own creator, but practiced my will?' (5) So he ever shouted to the wicked very mockingly.

Ahriman in this vision is neither actively involved in punishing the sinners, nor himself being punished - but instead mocks them for being stupid enough to follow him, which is an interesting twist on things. Then follows an epilogue, which stylistically reads like a later (maybe early Islamic-era?) insertion, but is still interesting:

1. Afterwards, Srosh the pious and Adar the angel took hold of my hand, (2) and brought me forth from that dark, terrible, fearful place, (3) and carried me to the eternal light, and the assembly of Ohrmazd and the archangels.

4. When I wished to offer homage before Ohrmazd. (5) And he was gracious and said thus: 'A perfect servant art thou, pious Arda Viraf, the messenger of the Mazdayasnians; go to the material world, (6) and as thou hast seen and understood, speak truly to the worlds; (7) for I, who am Ohrmazd, am with thee; (8) everyone who speaks correct and true, I honor and know; (9) so say to the wise'.

10. And when Ohrmazd spoke in this manner, I remained astonished, (11) for I saw a light, but I saw nobody; I also heard a voice, (12) and I understood that: 'This is Ohrmazd'.

There's a long-running tradition of a punishment/reward dynamic in Zoroastrianism, and there are a few references to individuals being tortured in hell or "purgatory" (such as the flawed hero Karsasp, who will only be redeemed when he slays the serpent Dahag at the end times). These kinds of elaborate accounts only pop up in late antiquity, but there is a long-running earlier tradition of ritual use of intoxicants - most notably Haoma (Soma), probably some kind of stimulant or a generic name for various intoxicants - which is likely to be directly tied to a later tradition of these "visions".

The difficulty of dating Arda Wiraz, accounting its predecessors, and other traditions makes it hard to say what, if any, might have been the connection between Christian "panoramas of Hell" and the Zoroastrian equivalents. There are many ways that influence could have flown either way, really, but I think these traditions make for a very interesting point of comparison.

/u/sunagainstgold has explained about the different ways angels have been seen.

/u/idjet has previously written about the Devil's pitchfork.

/u/Talondearg has written a 'brief history of Hell'

Your question is very broad, the above are a few highlights from the subreddit. There are thousands of doctoral theses and other scholarly works about Christian mythology. There is no particular start date for all of it. It's like asking "How did kings first get crowns?" -- different stories came to different places at different times. There are specific dates when the stories were first formally written down and compiled, but that's not when they first came into existence. Neither Dante Alighieri nor John Milton were first to the party.

Our friends at /r/academicbiblical might be able to help you.

The subreddit gets a lot of questions about John Milton's Paradise Lost, but most of the answers are not up to the current standard.

EDIT: You could also look at the Christianity section of the subreddit booklist.