1) Dunno why they are called creeps.
2) Minotaur, basic melee with axe. Archer, has a bow. Priest, heals and has some attack. Some catapult beast, throws rocks at buildings. Angels, make swooping attacks with two swords. Giants, huge monsters walking around with a pillar of stone they hit people with.
3) In beta 1 (engine test) they are extremely important, both because you need them to level up, and to push your own attack.
4) I don't know if they are refered to as creeps, but I don't think so.
5) In beta 1, engine test, the melee assassins would last about 20-30 seconds without items. Ranged assassins lasted significantly longer (but also ran out of mana so going back to the heal/mana beacon was still good).
Creeps are the major part of the "flow" of battle back and forth between your and your enemy's base. They do most of the fighting, and you play a single assassin taking part in that war, or a general with some units to command on your own. The creeps spawn continously, and increase in numbers and power as time goes along (in the beginning, only basic soldiers spawn, then archers, then priests, and so on).
