Didnt read the whole thing...
Car is still considered new, happened to me too 1 month after owning. I demanded the insurance company supply NEW OEM parts and gave hard facts. <30 days old, 1500miles, etc.
As for inusrance, my buddy works in a body shop and showed us a car Geiko had provided them to use for parts for another car. I cant remember what it was, but Geiko literally bought half a junked car for them to cut the parts out of. Request to take it to a shop you want.
We have had 2 accidents in 6 months, not at fault, and both time we took it to different shops that we picked out.
And for the diminished value, some states do it some don't. I was able to get $1500 for getting rear ended, and then argued nicely for another $380. You can wait till the car is in the shop, and even after its fixed. Just dont close your claim until you have it.