I'll start with the biggest issue; biting. It may be fine with you if she does that with you, if she does it with others they may not think it is fine at all. Biting dogs can turn into a legal problem.
Do a Google search for NILIF, it stands for nothing in life is free. Dogs have to earn resources, food is a resource. Training dogs to fit into your life safely & sanely is all about controlling resources. There are many resources, some pretty general, some specific to each individual dog.
The dog controls a resource, food, because you let her. No more free feeding, the dog has to earn that resource. Feed twice daily, by hand for every meal. Make the dog sit for every bite. The dog has to understand that you control that resource, and that a hand near food is a good thing. This will progress to tossing a bit of food in her bowl, then tossing a treat in her bowl while she is eating. You control that resource, and when you do the dog sees that only the best things happen.
Often you can only guess how a previously owned dog was treated, but by observing the present behavior you can see what you have to work with. Most dogs with behavioral issues that need attending are great dogs 90% of the time, it's the 10% of those issues that may need work, depending on what those issues are. I would be lying if I said none of my three terriers had no issues that I work on, these are just minor adjustments at this point, little annoyances that need some fine tuning.
A good example is Kaz, who came up to me for some attention while I've been typing this. He will often paw at your arm for attention, I don't want this,I ignore it, a chin on the leg gets my attention. I know he wanted some lap time, a resource. Chin on the leg, you get lap time, napping ATM.