I hope you wont decide to re-home her, she is just afraid and that wont last long. As for her nibbling your nails and "grooming" your arm hair it is a good sign. Birds communicate with their beaks, we learn to read them as to it being a good thing or not. My grey likes nibbling my fingers and never put on any pressure. If it were me I wouldn't try to train her to to do anything just yet. Gain her trust first doing the things the other members have suggested to you. Also what has been said about whistling is a very good idea. Greys love to whistle especially at dusk. They are also very good talkers and that will come in time, she may also have a vocabulary already since she is 8 years old, but not ready to come out with them yet. She will growl less and less and you'll know your are making headway with her. It sounds like her last owner was rough with her, and oven gloves! OMG!!