Answer:
I am the tool for inspiring many. Buy me in the store for not much more than a penny. Don't overuse me, or my usefulness will go. What am I?
I go inside boots and outside shoes. What am I?
I regularly change shape yet remain a sphere. I am always there but not often seen. What am I?
You may enter, but you may not come in. I have space, but no room, I have keys, but open no lock. What am I?
Never resting, never still. Moving silently from hill to hill. It does not walk, run or trot. All is cool where it is not. What is it?
I break away from my pack. I create holes in my victims. I can travel for miles and then disappear. I am part of a dying breed. What am I?