Whilst tethered shooting is available the LCD on camera's work very well and for real detailed stuff have hystograms etc. built in.
Getting the shot 'right' will be the same whether you are tethered or using the LCD on the Camera. You'll light and frame the shot, take a shot in manual mode, adjust, take a shot, adjust (this can be simplified I believe using some light meters that I THINK - someone please confirm - will give the light level when the flash fires rather than the ambient light ).
Once you have one shot setup right, all the other shots should be pretty much place object, shoot, place, shoot etc.
Unless there's a major depth of field/focus/framing/object size change you should be able to take the shots without changing anything once you have the settings sorted.
Canons often in dpreview are reported as having 'poor incandescent' white balance performance but I assume that can be sorted with RAW post processing.
That said I don't think you should work with ambient/mixed lighting. You should get a couple of flash guns, probably both with shoot through umbrella's, lightstands and tripod ( for the DSLR) so the lighting is consistant and your job a lot better.
Mixed lighting is going require you to post process EVERY image with white balance adjustments because the temperature will be changing all the time. If you work with flash ( or similar ) lighting your going to be working with consistant lighting so the white balance can be set on the camera and should not require changing shot to shot.
As for the DSLR to use, as I don't think you need tethered shooting ( and that's likely to require additional software), and after sorting money on lighting I'm guessing you'll have a $1500 budget. For that you'll need a DSLR and probably a couple of quality lenses, something like a macro capable 100mm and a 50mm.
That means the world is your oyster really, working at UK prices assuming a budget for the DSLR+lenses of £1100 , (it's easier for me that way - saves fishing out US vendors

) you'd probably be looking at something like :-
about £1100 for - Pentax K20D, Pentax smc FA 50mm f1.4 Lens, Pentax smc DFA 100mm f2.8 Macro Lens
about £1500 for - Nikon D90, Nikon 50mm F1.8D AF Nikkor Lens, Nikon 105mm F2.8G AF-S VR Micro Nikkor Lens
about £1000 for - Canon EOS 450D (XSi I think), Canon EF 50 mm f/1.8 II, Canon EF 100mm f/2.8 Macro USM
Personally I'd go for the K20D, the other two kits don't quite match it for price/value. They all have 2.8 100mm lenses but the Pentax option has the best 50mm.
All three kits ( plus money spent on proper lighting ) will do what you want, it's quite possible the Nikon and Canon experts can improve on the kits I put together but not sure how they'd match for price.