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.
What has wings, but can not fly. Is enclosed, but can outside also lie. Can open itself up, or close itself away. Is the place of kings and queens and doggerel of every means. What is it upon which I stand? Which can lead us to different lands.
What lies in a tunnel of darkness. That can only attack when pulled back?
It happens when something has been cut with H2O.
What is round as a dishpan, deep as a tub, and still the oceans couldn't fill it up?
You use it between your head and your toes, the more it works the thinner it grows.