1) Is it involuntary stopover? (stopover forced by earlier fully-booked flights don't count)
If yes, then one gets a room, if not, no. Award flights don't get a room as well.
2) Since it is less than 24 hours, the luggages go all the way to SFO.
p.s: Can we please have a sticky post regarding the stopover hotels provided by Asiana? OZ forum is flooded with this kind of questions and yet people don't bother to do a search.