/u/murder_cheeze has given a solid description of firing by rank, but since you asked about bullets I'll touch on those too. First I've got to make the distinction between smoothbore firearms and rifled firearms. Rifles have spiraling grooves cut into the inside of the barrel, so that the bullet spins as it exits and therefore flies more accurately. Smoothbore guns have no such grooves, or "rifling". Rifles, while more accurate, took longer to load because the bullets fit so firmly that it required more force to press the bullet down. It wasn't unheard of for some soldiers to use hammers to force the ramrod down the barrel. The ball might also be wrapped in greased cloth to help it slide down easier.

The Minie System solved this somewhat in the 19th century by having a bullet that expanded at the base when shot, so it could be loaded easier and quicker.

These bullets, both Minie and standard ball, would cause massive smashing damage when fired at a person. Modern bullets puncture skin and occasionally make clean exit wounds. These lead balls expanded and splintered bones, making full recovery sometimes impossible even for light wounds.

Aside from what everyone else has mentioned, I call your attention to the Ferguson Rifle which was a reasonably successful breechloader for it's time.

As for magazines, you won't find removable or fixed box magazines or tube magazines generally outside of cartridge arms. The two go hand in hand with each other.

/r/guns would probably be able to answer this question with absurd levels of detail. Finding videos of flintlock muskets on youtube might also be helpful.

In terms of guns with magazines, there were several, but the concept didn't really become practical until the invention of cartridges as we know them today. One of the more interesting designs was the Girandoni air rifle, which saw service in the Austrian army in 1780. This rifle was powered by a compressed air reservoir, and had a magazine capable of holding 20 rounds. It was fast, quiet, and didn't produce massive amounts of smoke like other guns of the time.

Another interesting weapon of the era was the Puckle gun. While it was never fielded by any military, this gun was in essence a very large revolver, and was demonstrated firing 63 rounds in 7 minutes (9 rounds per minute).

The cartridge as we know it today became popular in the 1860s, around the time of the american civil war. This invention allowed for innovations like the lever-action rifle and the gatling gun.

Can you give a date range? Nations involved maybe? I wouldn't want to ballpark it if you're writing something.

You should probably go with the Brown Bess. It was stood on end (or tilted; more in a minute), and a paper magazine would be used. The magazine would contain powder and ball. The paper shell was torn with the teeth, and the flash pan was prepped by pouring a small amount of powder from the cartridge. The rest of the powder was then poured down the barrel. Then, the cartridge would be rammed down the barrel in "reverse", with ball still inside, with the ramrod. It was then ready to fire.

Now, if they were firing by rank, it would go as follows:

1. The line is formed front to back by rows of soldiers who will comprise the separate volleys. We'll use three volleys in this example.

2. The order is made to make ready, then to aim. The men at the front will aim their weapons.

3. When the order to fire is given, they will fire.

4. The soldiers who have just fired will drop in place to one knee, and angle their weapons to reload. The lines behind them will advance one line past the men on their knee.

5. The second row fires, and then takes a knee to reload. The first row to fire will stand when done reloading.

6. The third row advances to the front and fires, then takes a knee.

7. The first row will then make it back to the front, and the cycle continues.

I hope that works!