Rear wheel bearings job...

I'm not totally sure yet if my rear wheel bearings are starting to go, but I don't want to go near my local dealer, so I'm going to leave my car with my local (very honest) mechanic...

A few questions: Is there a test (visual or otherwise) to see if the bearings are going. Right now the car rolls noisier than I recall, and while I hoped it was the tires, or my own bad memory, folks here have said it's probably the bearings...

Assuming it is the bearings, how difficult are they for a mechanic to change, is there any special equipment he might need (and would be unlikely to already have)? And, is there any unusual procedure he should follow, or thing he should be sure not to break while doing the change? My car is a '92LS-L AWD.

Lastly, does anyone have the updated part numbers for the bearings to be used?

THANKS!