I rescued a German Shepard from about the same situation. Getting her fixed will calm her down A TON! she will also learn that you are trustworthy and that you are nice to her. We put our dog in one of those week long dog training camps. They stay there for the entire week night and day, and when they come out they are TOTALLY changed for the better. My german shepherd is 11 now and he is so loving and protecting and is the best dog we've ever had. Even though he had a rough start, all these steps really help to calm the dogs down!

Good luck

She will calm down when she starts getting regular exercise and mental stimulation. Getting her spayed will keep unwanted litters from happening.

Do you have dog experience or access to a knowledgable dog trainer?

This is a big deal. If she has had protection training (ie bitework) from the Police, it is going to be a huge liablity for you. You need to know what you are getting into and if you can handle her. I am not saying because she was trained to bite she is dangerous, but if she has been "ruined" like you say, there may be some behavioral issues that come up. You need to be able to handle the situation if there is a problem.
Remember, if she bites someone, they will bring that up.

As for being hyper, working dogs have alot of energy, and, of course, the being crated all the time contributes to the extra energy. . If you do take her, she should mellow out a bit if you give her a good run every day (mine runs with me plus a good game of fetch).
GSDs are very intelligent and very active. You should be committed to exercising her well everyday. Training helps to tire them out as well and provided that needed mental stimulation.
A bored dog with too much energy can be extremely destructive and can lead to other behavior issues.

Its hard to say without knowing the dog and the situation. But dogs are very adaptable. Its really going to depend on the dog and what issues she may have. She may turn out to be a wonderful companion, or a huge liability.

My oldest GSD is a Police dog washout. He was trained in protection work. We have had no issues until the lab came along. He became very protective of the puppy. It is something we worked through but still have to deal with. He is also the most loving loyal dog and is my ever watchful companion.

people dont know this, but kiddle and wet food are BAD. dogs are pretty much wolves, and wolves eat grass and meat, dont little crumbely balls. give him some meat, and have him checked for worms and stuf.

also, if he is fixed, it could have done something to him. I know if someone gave me surgery so my balls dident work I wouldent wannna do anything

feed him