Hello Jayblade and welcome to our family, its great that you could join us and we look forward to hearing more about you and Bella.
This must be your first bird since you sound very new to owning a grey. Bella is beginning to show her independence, she wants to do things on her terms and if you want to gain her trust then you are going to have to earn it.
Do not grab her legs and hold her wings to get her to stay with you, she doesn't want you to and she is showing her displeasure by biting and if you don't heed her warnings it will only get worse.
Open her door and allow her to come out on her own and if she doesn't want to then that is ok, she will when she is ready, don't force her to do anything she doesn't want as it will only make it worse for you.
Provide several rough type perches like concrete near her food and water bowls where she has to use them, they do a pretty good job of keeping the nails from getting too long.
I want you to read thru as many of the endless threads we have here for lots of useful and helpful information and do ask questions you may have and we will help you in any way we can.
We love pictures here so if you have some of Bella you would share with us we would love to see her.