Answer:
I am a protector. I sit on a bridge. One person can see right through me, while others wonder what I hide. What am I?
If I drink I die. If I eat I am fine. What am I?
You see a boat filled with people. It has not sunk but when you look again you don't see a single person on the boat. Why?
You turn me over after you have travelled far.
I wear a red robe with staff in hand and a stone in my throat.
Whoever made me don't want me. Whoever bought me don't need me. Whoever use me don't know me.