1. you do not need to pay first, except for any deductables (it's the other side's fault, so deductable should not apply here).
2. you should be able to go to any repaire shop you choose (the discount doesn't benefit you)
I was hit a few months ago, the repair bill didn't even come to me and I didn't pay a cent, the other person's insurance handled everything.
which insurance company do you use?