A few problems

First problem: I'm trying to create a bow and arrow but I am having some issues. First of all I don't know how to give the bow an animation for when it is being pulled back like vanilla bows have, second I don't know how to make a model for the arrows and third it doesn't work like a normal bow when firing because no matter how far back I charge it, all the arrows go the same distance.

Second Proble: How do I make mob and block models?

Third problem: I have made some custom trees but I don't know how to make a sapling