Matt, I am so sorry to hear about that. I would have been just as pissed. I remember when my brother's '84 was stolen we drove around for hours looking for someones ass to beat!
After getting screwed over early on with the first cars I owned I started learning how to do "everything" so that I wouldnt have to rely on anyone. Problem with trying to do everything yourself though is that I never seem to complete the projects
As far as body and paint, which I dont have room for nor am I an expert, I will only deal with someone I know personally. Though if I ever get my dream garage built I will probably be laying down my own paint too
Unless Im not seeing something right in the pic, looks like everything on the doors were in the process of getting shaved? Including the mirrors which I dont even see the holes for. If this is the case then thats why the door panels would be removed. Are they in the trunk or still at the shop? Did you ask them to shave everything? To do the body work and prep right everything on the body would be removed, bumpers, trim, handles, mirrors, locks etc. (so again it would be necessary to remove the panels). Dont think its necessary to remove the header panel, but??
Anyway, are you still out of town? Have you been able to have police or anyone get into the shop and look around?
Otherwise, keep a look out for another Regal out there with your parts as the stuff that is missing is specific enough that you know what they are going on. Header panel would indicate a Regal anyway although the other parts would fit any gbody. Try to make sure your stuff isnt in the bodyshop building though if you can. Only missing part that doesnt make sense being removed from the car in a bodyshop is the turbo