The most important element is your eyes. Technically, its my understanding that Maxim & the lad mags use 120mm film, not digital (althought that could have changed lately). SI uses whatever the photographer wants. In various videos of SI shoots, I've seen Walter Iooss using everything from 35mm film to an RZ67 to a big Canon digital (take your pick), (and only one assistand holding a plain round reflector). One year someone even used a throw-away for a section. Since the whole industry is in transition, the answer you get today may be invalid next week. Remember that with SI, they have tons of assistants so what they bring is not an issue, but in the end, you can do great images with one camera, a model and nothing else. Which brings up another point. All of the mags that shoot this type of image use big crews - seperate top makeup & hair people, wardrobe stylists, set designers, several assistants, an art director, editor, etc. A lot of it's really bogus and unnecassary (IMO) and simply a way to justify big budgets and stroke celebrity egos, but that's what they do.
As for the lighting and such, well, that's photography. Knowing when and where to shoot, and how to make the model look good when you get there is what its all about, and just takes experience and being willing to work hard to get that. For example, I've been known to spend most of the day NOT shooting, because I'm waiting for the good light that comes at sunset. And there are shots you can get in certain locations, like Florida, that you can't get in Wisconson (I think - I've never been to Wisconson). Sometimes you can't fake it. These shots of Erika and Mandy were done in Sarasota, FL a couple years apart. I couldn't have done them like this here in CA, but I could do something else. (Actually, now that I think of it, I could probably have done the sunset with Mandy in CA, but we only get those sunsets in winter. Also, the water is usually pretty cold and Mandy is not in CA).
One suggestion I have if you want to see how the pros do it, is watch every news story or video that shows behind-the-scenes on these things. Whenever SI or Maxim comes out with a swimsuit issue or some hot celeb, they always show a little bit of the shoot on the tabloid shows like Extra or Entertainment Tonite. SI even does a 1 hour special on VH1 every year (and they re-run the earlier ones all week). You can pick up a lot of "how-they-do-that" tips from just a few seconds of that.
Andy Pearlman Studio