What Am I Riddles

Question: My thickness is no more than a few centimeters, yet my depth can span to infinity. Although mundane, I intimidate most animals. When in my presence, you will inevitably follow me. What am I?

Question: The person who buys me doesn't need me, the person who makes me doesn't want me, and the person who uses me can't appreciate me.

What am I?

Question: What has 4 fingers and a thumb, but is not living?

Question: I take what you receive and surrender it all by waving my flag.What am I?

Question: I wear a red coat and have a stone in my throat.

What am I?