I missed the part about wanting to breed the mare... Hopefully not.
To the OP, now that you have her, you should start a thread about her manners. The biting is not acceptable at any time. Eating or not eating, she can tell if your hand is there. She can feel difference between the food and your hand before the teeth get out.
Please do spend a lot of time with ground work on her. It will pay off in spades - through a respectful, safe horse and one that is easier to work with as training progresses. And remember, it is often little steps...
I'll try to watch for a new thread about her manners towards you. no biting, no pushing, stand quietly, leading at your side, etc. etc.
Also, please only post real-life situations with your mare. Not someone else's and not trying to foresee what might happen. There are enough guesses and interpretations that have to be made when working with horses. We don't need extras thrown in! :)