Move slow and gentle with her. Tell her what a good girl she is. Find something she likes as a treat and give her bits of that whenever she IS a good girl. You may want to work with her AWAY from the cage, out of sight. You may want to consider clipping her wings if she is fully flighted. Being dependent on the parront (you) for transportation usually gives the little feather butts an attitude adjustment.
If she bites when she is on your hand, there is a little move called the earthquake (a gentle shake to put her off balance, not shake off, just off balance) that will teach her not to bite. They are very smart so you tell her No Bite, Gentle, whatever words you want to use and she'll catch on.
Keep training sessions short 10-15 minutes a couple times a day away from the cage to work with her on Step Ups. Praise often and effusively, they LOVE it
As for 'teaching' them to talk, if you talk to her, she will probably learn to talk back. Not ALL quakers talk, but most do. Talk to her, sing to her, tell her what you're doing (opening the cage, taking out/putting in food and water, cleaning the cage, putting in fun new toys, etc.), ask her to step up, be a good girl, go nite nite, whatever.
It sounds like you want to give your baby a happy home. Remember you will have her up to 30 years so she is NOT 'too old' to learn. They learn thru their entire lives, new phrases, new words, and they can and do talk in context!

Good luck working with your little one. Let us know how things are going and ask any questions you may have. We are all more than willing to share our experiences with you.