First off let me just say how sorry I am that a bad driver got to your B. Me and a few others have had our own little problems with bad drivers. I would like to also say make them pay through insurance, if it gets bad enough for them it's one less bad driver on the street. Anyhow. . .
When I got rear ended last year I got the same husband story. Make life simple for yourself, go through th insurance. Screw the other people, she might pay but if she doesn't well let's say up the creek without a paddle.
As far as body parts coming painted. No they do not. Everytime I went to a body shop to get an estimate i was told that the part would have to come from the dealership and it would need to be painted. I have my connections to a Toyota/Scion Dealer and even they told me that I would have to get it painted.
Lastly, forget the junkyard angle. All the junkyards in MD, VA, and Washington DC will only sell the complete bumpers assembly. That includes the bumper reinforcement, plastic covers, and some other random body parts. I still haven't fixed my rear bumper and I am still waiting for my check. I got burned so I'm hoping my negative angle will make sure somebody else doesn't get burned.
As far as estimates for damage to the rear bumper, dealer body shop wanted about $500 and the other body shops wanted roughly $800. To be honest after talking with the other body shops, I'd rather pay out the $800 bucks.