Answer:
What can touch someone once and last them a life time?
What goes further the slower it goes?
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.
I'm light as a feather, yet the strongest man can't hold me for more than 5 minutes.
Five hundred begins it, five hundred ends it. Five in the middle is seen. First of all figures, the first of all letters. Take up their stations between. Join all together, and then you will bring before you the name of an eminent king.
You use it between your head and your toes, the more it works the thinner it grows.