Answer:
I store fire-breathing animals.
I encourage people to run home and steal
You use a knife to slice my head and weep beside me when I am dead.
I'm as simple as a circle worthless as a leader; but when I follow a group their strength increases tenfold. By myself I'm practically nothing.
I have cities without people forests without trees and oceans without water. What am I?
Black we are and much admired. Many seek us if they are tired. We tire the horse, and comfort man, and turn White when we've fulfilled your plan.