Answer:
I fly forever Rest never.
I make things short but I am pretty long myself
I begin your sentences.
I have no voice but I can teach you all there is to know. I have spines and hinges but I am not a door. Once I've told you all, I cannot tell you more. 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?
Pirates put their booty in it.