Hi Jeff,
In terms of getting ceiling speakers to work with a computer, potentially via wifi/bluetooth, I can't offer too many suggestions 'cos I've never done it and don't know what sort of kit is out there to achieve it...although I'm sure there is plenty.
Mark, in terms of wall mounting satellite speakers I would err on the side of caution as most of the ones I've come across need to be used with a sub as the drive units in the speakers are tiny and the musicality of the speaker is poor on it's own...I'm thinking along the lines of the KEF 'Eggs' that are/were popular in surround systems, used on their own they have virtually no bass response but once combined with a sub they work quite well for films, still wouldn't use 'em for music though
About the best satellite / sub system I saw which made a good attempt at music was one of the M & K packages but they were slightly bigger which obviously helps and a lot more expensive.
I believe that KEF did make dedicated in ceiling speakers in the past (think I installed some once when working at the hifi shop if memory serves) and although they are fairly shallow in design, the ones I remember were the size of a dinner plate so they had a fairly good sized drive unit in them and therefore bass response was pretty good. On the install we did they were mounted into a plaster board false ceiling in a barn conversion and there was nothing behind them as such.