if the rim is bent, i would replace it with a new sun rim and also all the spokes with new ones (sapim race).

this isn't a necessity. some mechanics are great at truing bent rims (with a little pounding). i am not.

you can use the upside-down bike frame as a truing stand. (see sheldon's wheelbuilding page.)

if the axle is bent, i would replace it with a used axle from the bin at the co-op for $5. if i couldn't find one, i'd buy a new wheels manufacturing axle off ebay.

if just a few spokes need to be replaced, i'd take it to the lbs and buy a few spokes. if it's on the drive side, and i didn't have the right freewheel tool, ask the lbs to remove the cluster as well.