More amazing news on the test results!
My VIN is 5004, so you're saying I have the extra rear bumper? Awesome if so. (I do not have the rear-facing child seats). The driver at the rear was a middle-aged man. No teenagers involved! I've no idea why he didn't see the stopped traffic.
I was able to drive off; all the lights worked. The trunk couldn't be opened though - any kids would have had to climb out over the back seat. The charge port worked, but the car insisted it was always open even when closed. No glass broken, expect for a chip on the rear edge of the pano roof, perhaps caused by the tail being pushed up against it.
Going through my mind immediately post-crash, while the car was still rolling, was what was I supposed to do on the main screen, put it in tow mode or something? My poor panicked brain. It seemed to take a while before realizing that I needed to apply the brakes to stop! It freaked me out when I realized I was still moving - maybe the van behind was still pushing me? It all happened so quickly. I've seen people suggesting a "crash mode" for the central display, and I agree that would be a useful thing to have. Towing/flat bed instructions etc.
Oddly, after the crash there was a small pool of water just in front of the right-rear wheel, with a couple of drops on the body of the car that hadn't fully dripped down. I don't recall the AC causing a pool in that location before. Any ideas what could have leaked/condensed from that location?