I'm not sure about the white grille - you'd need to ask Dave/Dina. I think I may have done so several years ago and it was possible, but not cheap.

As to mounted in the ceiling, I think if there is the depth between the face of the ceiling and what's above it, and space enough between the joists, it would be possible to mount them flush. I recall a post from a few years ago that someone did this. As I recall, they used the existing mount holes in the cabinet and also put one or two studs on the opposite end, and bolted/screwed everything to whatever was above. If I had mounted them to the ceiling in my room, that's how I would have done them (I'm in a single story, so would have bolted to the flooring in the attic above). That said, I would have mounted the cabinet backs to the ceiling so they hung down and not cut holes into the ceiling/attic although the ceiling does also have "can" lights which protrude into the attic.