Answer:
What I am filled, I can point the way. When I am empty. Nothing moves me. I have two skins. One without and one within.
I run around the city, but I never move.
I'm not man's best friend, I'm their enemy, I can mark your end, yet you do not see me, I am very small, but very tough, If you have me, then you have it rough.
It's like food but water kills it. What is it?
If you happen to wear one of these warm garments around, you might get doused in red paint.
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.