No. There are no orgies.
Which is the simple answer; the longer answer goes something like this. Sexuality is viewed as a sacred thing, a part of each person that s/he needs to be aware of and tend to properly. In my opinion, being informed is possibly the most important part of the whole deal, so I'd recommend checking out websites that are actually informative, such as ScarletTeen for teenagers and Scarlet Letters for adults. (Both these sites are aimed at women, namely because I am one. If you have a suggestion for guys, let me hear it.) Safe sex is important, people. If you're going to get sexually involved (and that includes the stuff that's not out-and-out intercourse), make sure you know what's going on. Protection matters. Your emotional readiness matters. Education is important, and in the American system, it's virtually impossible to get.
There may be some groups out there that have orgies. I'd be careful around them, if I were you; that may not be the most emotionally or physically healthy setup. Groups whose rituals involve sex are definitely the exception to the rule.
You'll probably hear something about a Great Rite, which is supposedly the joining of the God and Goddess principles in sex. You ask me, I say it's highly overrated, and the whole "polarity" thing is pretty much bunk as far as I'm concerned--but then, maybe that's the queergirl speaking. It's very rare, and chances are excellent that you'll never encounter it.
As far as "Sex Magick" goes, it's way too hyped. Take everything you hear with a grain of salt. Granted, there is a lot of energy raised by the whole shebang--how could there not be? Don't use it unless your partner is okay with that and you've discussed it beforehand. Karma can rip you a new one over things like that. And for your own sake, study a lot. This is one of things where it's just better not to mess up.
When it comes to body image, Pagans are pretty flexible as a whole. Bodies are bodies. They're supposed to be healthy, so make sure you're taking your vitamins and keeping yourself in reasonable shape, cholesterol, blood-pressure and diet wise, but other than that, hey. There's a reason real women don't look like supermodels, and there's a reason real men aren't used for CK underwear ads. They're fictions. Not even aliens from another planet, tempting as that is to believe; they're anomalies, aberrations carefully cultivated to prey on our fears. In real life, we're human. And that's okay.