Ok, a bit more time now
I think the most important thing is getting the pics right in the camera. PS can make a great pic look excellent but otherwise it's like using Permatex on a Cman raised panel ratchet
I'd get the lighting the way you want it first. Then lock everything down and keep the setup intact (room allowing...). Do a custom white balance with that setup. Now, take a series of manual exposure shots (stopped down for depth-of-field), load them into PS and look at the histograms. Don't trust the histogram of your camera.
The perfect thing to shoot would be a
Gretag Macbeth Mini ColorChecker Chart. I'm sure you can find one for a better price than Amazon...
Another option is a
Whibal. That also is the perfect thing to shoot for the white balance. They make various kinds and sizes.
Otherwise, get a cheap Kodak grey card for the white balance. Avoid white paper.
When you load the shot into PS, you want the black square at around (10,10,10) and the white one at about (245,245,245). The red, green, and blue squares (above the grey scale row on the Gretag) should NOT max out the corresponding color values but should be close.
Pick the best exposure and note the aperture and shutter speed. If you can't get the black to be completely black, that's fine. It's
way more important to get the white as close to white (without blowing it out) as you can due to the way the color values are stored (most of the information is in the lighter tones). You can always knock the black down in PS, but pulling up the dark areas is ugly...
Since your lighting doesn't change, you only have to do this whole thing once and then you're set to take product shots quickly and with great results. This also minimizes the the time you spend in PS. My rule of thumb is if it takes me more than 2 min per shot in PS, I didn't do a good enough job with the camera (unless I'm planning to print a 30x45...).
More on the PS side of things later...