Hey hlasdf,
Welcome to this forum! It's good to see you getting lots of replies.
I wanted to chime in, based on the information you've given here, plus one of your posts on a different forum - it sounds to me like you're really pushing your little birdie to do things it doesn't want too fast, too soon. I can totally get why it's getting angry and biting - can you imagine if you were to sit down and try to surf the net or do work on your computer, and this annoying giant the size of a skyscraper keeps putting its fingers between you and the computer to interrupt you?
Just in general, I think you need to go a lot slower and calmer with this. Try to manage situations so that the bird getting into things/places you don't want never happens - it's better to prevent a problem than to have to go in and stop it afterwards. And, try to make whatever you want your bird to do MORE fun than what it's already doing. I'd even go so far as to leave boring toys on the countertop, and then give it fun shredding toys as a reward for stepping up without biting... things like that. A big, fat, wide toy is easier for you to put between your bird's beak and your fingers than a small treat, too, so that can help with the finger-chomping you mentioned.
Prevent/ignore the bad and reward the good is my motto, for all the animals I work with, and it's worked well for me. Good luck!

And please don't give up, and DO expect it to take some time. I know what it's like to have a bitey bird (my GCC is called Shark for a reason...), and even though it's so easy to get frustrated at why-is-this-bird-still-biting-can't-it-see-I-want-to-love-it-GRARGH, having a zen attitude of "it's ok, that's how the bird feels about me right now, so I'll let it go and try again later" really pays off way more than trying to force the bird to accept your demands immediately.