For instance, I fail to see how, if you are shooting in manual as you advise, you are ever at "the vagueries [sic] of in-camera metering from shot to shot." whether in a studio or not.
Vagueries is a legal spelling, according to Wiktionary, albeit a fairly rare one.
I assume what the author means is that in-camera metering gives you an overall measurement of the shot as a whole, but it will vary from shot to shot as people change angles and their tuxes reflect more or less light. Therefore, it isn't as ideal a tool as an intern walking around with a good light meter and taking measurements at various parts of your set.
That said, this is me speaking with my video hat on. I have no idea how you would do the same thing when using flashes without really annoying the heck out of your subject.
As for the other comment, the usual
goal is to light and expose the shot properly so that you don't clip any important white detail and so that important dark detail doesn't get lost in the mud. What constitutes "important" white/dark detail, however, varies....
Will reflectors help me avoid the necessity of using a 4 light set up.
Depends on the look you're trying to achieve. I've seen a lot of nice portrait shots taken with only a key light and a fill. That said, sometimes you want a backlight on the person and/or a light on the background.
I'd be surprised if a reflector were ever useful as an alternative to a backlight or a background light, but you might be able to get away with using a reflector instead of a fill light in some situations. I'm not sure how well that would work in practice—it would depend in part on on the number of people in the shot, on how reflective the reflector is, and on whether you can come up with a position where it reflects enough of your key light or backlight to do any good without blocking the shot.