You probably can't go wrong with most bearing brands out there, but I always recommend and go with National. Just about any store should have them. When I bought mine they were at O'Reilly. You'll also need new seals if they replace the inner bearings, which it sounds like they will.
The wheel bearing cups/races only
need to be replaced if they're uneven, pitted, corroded, or out of shape. However, if you've never had them replaced it's probably a good idea since someone's already in there. It shouldn't be much more time for him to do them.
Check out
the bearing howto for model numbers and quantities.