I'm installing tile over backerboard. The backerboard transitions to
sheetrock. I'd like to overlap the tile 1/4" to 1/2" onto the drywall
(this should make the transition more attractive)...

Anyway:

1) Is there any reason I shouldn't do this?

2) Should I prime the sheetrock first, or just install the tile, then prime
and paint up to the tile.

Thanks in advance,

Kyle