I can't think of anything worse than putting all that modern crap on an old building, it just looks wrong.
It would be better to leave it to crumble away.
Yes they are Bachmann bogies.
There is a small round stub that fits into the middle of the bogie and then
use a small screw and washer to keep it in place.
You never know, they could be next on the list, but don't hold your breath.
I would like a grey one. Never liked them at first but now they have grown on me.
Shapeways 42ft 3d printed 42ft flat wagons.
I got these about 2 years ago and finally got them finished.
They are very nicely printed and I used Bachmann bogies and Railtec transfers.