What Am I Riddles

Question: I am in everything and in nothing, what am I?

Question: What is only a small box but can weigh over a hundred pounds?

Question: What belongs to you but others use it more than you do?

Question: What has a foot but no leg?

Question: Crawls over pages and fells wild beasts.
Helps guide you along in your home and on streets.

What is it?