Crucifixion first appears in our records as a form of punishment and death employed by the Persians (see Herodotus Hist i.128.2, iii.132.2, 159.1), and later taken over by some Greeks, including Alexander the Great, and also Romans. The practice appears to have had usage in other ancient cultures too, however, see Hengel Crucifixion, p22. Jospehus records that Antiochus IV Epiphanes crucified Jews who would not accept Hellenisation, (Antiqu. xii.240-41) as well as Alexxander Jannaeus crucifying 800 rebels from Bethome (Wars i.4.6, Antiqu. xiii.14.2-3).

The Romans generally reserved crucifixion to slaves and non-citizens; generally citizens sentenced to death were decapitated. They probably learnt it from the Carthaginians. Actual practice could vary, including a stake, a stake with a crossbeam (T shape), or a stake with an intermediate crossbeam (t shape). Those condemned to death might often be flogged beforehand, a punishment sometimes enough to kill by itself. You can read attestation of pre-crucifixion torture in Lucian’s Piscator, as well as Cicero, 2 Verres 5.62.171). Both Clodius History, and Plautus Miles Gloriosus 359 attest to the practice of the condemned carrying the crossbeam to the place of crucifixion.

Generally they were fastened to the post before it was raised from the ground, this might be commonly done with ropes, though nails are possible (3rd century AD text Apotelesmatica 4.198f concurs with this detail, see Hengel, p9; as does Seneca in Dial 7.19.3, and Josephus Wars 3.341); nails would have to be driven through the wrist rather than the arms, unless the victim was both nailed and tied. As for length of time, Seneca in Epistle 101 seems to suggest that it is a long and drawn out way to die.

According to Roman sources, the method was generally used for slaves and as a form of state-sponsored terrorism against foreign rebells. For the former, see Tacitus Annales 14.42, 45 as well as Juvenal Satires 6.219-223, for the later, Strabo 3.4.18, as well as Josephus Wars 5.449-51). However, there are instances of citizens being executed, despite legal protection against torture. For example, Livy 30:40.13 records Scipio crucifying deserters.

Post-death, bodies could be left exposed, brought down and abused for public propaganda purposes, or handed over to the families. The latter practice is attested by Philo in Flaccus 83 for Alexandria, and by Josephus in Wars 4.317 for Jerusalem. There is no conclusive medical opinion on the means of death, and of course it may have varied for individuals. There is a strong leaning towards asphyxiation particularly in cases where arms were raised upwards and there was no possibility to support one’s weight. In such circumstances, the victim simply cannot support their weight to breathe as they become increasingly exhausted. For further reading on this in Maslen and Mitchell, “Medical Theories” (see reference below)

The absolute best book in this area remains Martin Hengel’s Crucifixion. The aforementioned studies on medical causes are Maslen M. and Mitchell, P. “[Medical Theories on the Cause of Death in Crucifixion] (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1420788/)” Journal of the Royal Society of Medicine 99 (2006), 185-88

I know that's not everything, but all I've got to hand.

Great question, why would Jesus drag a cross up the hill. I was taught, that others were on crosses next to him. I was taught that that is how they killed people at that time. So I imagine wood was scarce at that time and place, wouldn't they reuse the crosses? Surely they knew how to recycle. So what's the deal with Jesus getting a brand new cross to drag up the hill? Wouldn't Jesus followers want to keep the cross as a souvenir? Like the cloth that wiped his face? or the spear that they allegedly stuck him with? I would think someone would want to save the cross, maybe carve out pieces of it to sell to followers?

I can't answer all your questions, but I can a few of them. The Romans reserved crucifixion for slaves and pirates. If it was determined that you deserved a quick death, they would break your legs first, and you would die in a day or two at most, from suffocation. If they didn't break your legs, you would stay up there for days and probably die of dehydration. During spartacus' rebellion, 5000 slaves were crucified along a road leading to Rome as a warning for slaves to know their place. Roman citizens were thrown off a sort of cliff side to be executed, and non citizens would be flogged and beheaded, only slaves and pirates got the cross, I don't think a crucifixion would draw too much of a crowd. Hopefully a flaired user can go into more depth for you.