General advice a the end, or just speak to me when we next see each other. Specific points in response to what's already been said, follows:
Agree that the best way to trip the lights is wirelessly with their built in slave units if that is feasible. Works best if you have a separate flash unit that you can first away from the subject (just point it straight up) and fire it at its weakest setting. Not having to use a sync cable means more flexibility in movement, no worries about tripping and sending equipment crashing, and if you're sharing, no one person at a time with a hassle to go from camera to camera.
Number of lights completely depends on the lighting you are trying to recreate. Lighting setups can vary from no monoblocs to 18 or more units to achieve different things. Two lights on the model are enough for 90% of the effects around, and then it depends on whether you need to light the background as well. I personally have three units at my disposal, and while it is sometimes slightly lacking (usually when I want to mess with the background as well as the subject), I get by perfectly fine. In fact one of my units has been down and I just did a shoot the other day with just the two, and it didn't stop me from getting stuff I am happy with. And many of the shots that day were shot with just the single 'bloc.
I wouldn't exactly say four is a typical number.
Evaluating exposure on small LCD is poor, but the histogram is usually accurate although they do have their various indiosyncracies as well.
IMO more lights is nice, but doesn't just limit the movement of the model. To be honest I think the bigger problem is limiting the photographer in terms of distracting his/her attention; particularly when you're new to all this, you should be concentrating on the sitter and not on your lights.
Rumraisin, the reason to remove underwear is not that it won't show in the cloths. It's if you're doing nude work, underwear has a tendancy to leave markings on the skin that will ruin the shot. Nothing to do with them showing under the clothes!