Answer:
Used left or right, I get to travel over cobblestone or gravel. Used up, I vie for sweet success, used down, I cause men great duress.
Look into my face and I'm everybody. Scratch my back and I'm nobody.
Five men were eating apples, A finished before B, but behind C. D finished before E, but behind B. What was the finishing order?
I build up castles. I tear down mountains. I make some men blind. I help others to see.
It doesn't live within a house, nor does it live without. Most will use it when they come in, and again when they go out.
What did the piece of wood say when he saw the screwdriver and screws approaching?