1. afaik "deaths" from heavy weapons are more difficult to recover (less healed units if the battle is won)
2. if the unit on the rear kills faster (higher lethality, higher attack or AP weapons or a combination of those) than the unit on the front, yes (less men, more morale problems)
3 & 4. don't know
5 armour and shield, arrows and slings don't make a difference (the shield bonus is depending on the positions of the unit that is firing: 100% on front, 0% on rear, and afaik 50% on flanks)
6 the same as above, armour and shield
7 I think not. Usually I attack phalanxs on flanks when already engaged on front
8 see above