Elliot, you should probably discourage the finger nibbling if it turns into biting, just don't let it get started, he thinks its fun but its not if it leads to biting. Give him some foot toys to play with, something else to nibble on besides your fingers.
If he won't accept any new perches then you might have to take him in to the vet for trimmings, they have a dremmel tool that takes care of it in minutes.
when you do get new perches or anything new for him, lay them where he can see them and get used to them before you put them in his cage.