[JayG]

you can get your car fixed where ever you want. Generally they will accept the insurance quote. Ifthey have higher costs or find additional work needed, they will contact the insurance company and deal with it
Find the best body shop you can

Since it wasn't your fault, you have some leverage
also don't forget to go see a doctor and make sure you had no injuries. Even a slight rear end collision can cause back and neck problems, sometimes it doesn't show up for a little bit
The other guys insurance will cover all your medical bills including physical therapy

And don't forget the rental car the other insurance will pay for until yours is fixed

You may want to speak with an personal injury lawyer, at least for a consult