What would you like to ask?parrot feather plucking/chewing?

Today I rescued a male eclectus parrot. He is three years old. I have had him only a few hours and he is very sweet. he whistles and mimicks whistles and has even said a few words. He steps right up on your hand. He enjoyed a boiled egg some apple and his food. I have no idea of his back ground and am not an expert when it comes to birds but i just really care about him.
He plucks or it looks like chews his feathers. his skin is not exposed, it is grey and still coverd. Is that good? I cant imagine that he has been badly abused he quit shivering after about three hours and relaxed on my shoulder. still something just cant be right, he seems angry when he messes with his feathers, yet he is so sweet. I have been ignoring him when he plucks but really it is driving me crazy. Did he come from a good home and that is just the way he will always be? or was he ignored neglected and not given a proper diet? i am thinking # one would be to get him healthy and give him a lot of positive attention. i need help and advise from those more experienced than i. what should i get from the grocery and pet stores or how about activities for him.
he was checked by a vet and is supposedly healthy, his opinion was neglect. can the feather chewing/plucking be stopped. HELP! also how about a good bath?