Natasha, the first thing you need to understand is that this bird
isn't "bad"; instead, he is seriously frightened and needs gentleness
and understanding. So in order of importance, I would suggest the
following:
1. Get him thoroughly checked by an experienced avian (bird)
vet - NOT a dog and cat vet. I cannot tell from what you describe if
his eating habits are 'normal' or not, but he needs vetting so you can
deal with any possible medical problems. An experienced avian vet will
also educate you about diet and lots of other important stuff.
2. The swaying you describe could easily be what behaviourists
call "stereotypical behaviours." These are an animal's response to a
total lack of enrichment in their lives, which sounds like his
previous home. (Visualize a lion in a zoo, pacing and pacing and
pacing.) As you get him involved in interesting things like foraging
and play, that behaviour should decrease and maybe even go away
eventually.
3. Parrots guard their cages (their territory) especially when
they are anxious and frightened - this is perfectly normal. He can
learn he does not need to be aggressive as he learns to trust you and
you learn to trust him.
There are good books and tapes to help you, Natasha - especially by
trainer Barbara Heidenreich. You can access her stuff through
www.goodbirdinc.com. Another trainer, Rebecca O'Connor, also has an
excellent book, A PARROT FOR LIFE, which is available through
www.amazon.com.
The main thing is to be very, VERY patient. Your little guy has had a
very bad time with humans and you need to go at his speed as he learns
you are not like them. And bless you for giving this little cutie
another chance, Natasha!
Liz