First off, if a shop uses aftermarket parts, it's not their choice, it's the insurance companys...If your policy states that the ins co. can use any parts they deem acceptable (not just OEM), they will ONLY pay for aftermarket parts. Since this isn't your ins Co. (you are the claimant) Their rules don't apply so you can demand OEM ONLY...just for the record, OEM does include salvage parts. No worries with salvage though, the parts have to be off of the same year or newer vehicle. DO NOT UNDER ANY CIRCUMSTANCES LET THEM USE SALVAGE SUSPENSION. Any other parts should be fine.
Don't worry about the frame, any good body shop can straighten a frame better than what it originally was (yes, your frame was probably already out of wack. Most of them are). Side hits on a frame are usually easier to fix than front hits (front hits tend to "diamond" the frame).
In this area, Ins co don't consider totalling a vehicle until it is around 70-80% of the value (never seen 55%...glad I don't!)
AS a claimant, they need YOUR permission to total the vehicle. I have fixed cars at 2-3 times their value when the claimant refused a total. It's a long road but it can be done.
This is the crap I deal with all day everyday. I'm an estimator/project manager at a Large body shop...I deal with INS cos and their games 5 days a week. Just e-mail me if you need anymore help...
One last thing - What's the insureds Insurance company? Some are definately better than others.