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.
This only turns over once you have travelled very far. What is it?
Kills the bad ones and the sad ones. Tightens to fit, so one size fits.
You will find me with four legs, but no hair. People ride me for hours, but I don't go anywhere without needing to be tugged. Jerked or turned on, I always manage to be ready for work.
It's like food but water kills it. What is it?
What is so fragile that saying its name breaks it?