Very interesting topic indeed. I'll share my experience and thoughts on this...
I've seen countless times people wanting to be cute, but only do so once labelled as a couple, either by themselves or others. Now what's interesting here, is that at least from my experience, things seems to be going the opposite way. By that, most people within our network of friends begin acting all "cutesy" and shit way before they start "going out" officially. So in that respect, I reckon, at least from the people in our nearby schools, the label of a couple poses no halt in what they can and can't do. Really, it only ever applies to sex, which makes it look shunned upon. But then again, everyone still congratulates he or she for actually managing to get some.
As for the whole cheating part..Well, that has mixed feelings. Generally, the longer you're in a relationship, those are the people who genuinely get hurt. If its say nothing more than 6 months, people within our area dont get all that upset. The way myself and many others see it, is that you enjoy the time you had with them. Whether or not they cheated on you, you should've enjoyed the time you two had, and not let the fact they cheated make the experience feel any lesser. That's why my friends and I dont exactly care if we're cheated on or break up.
As for the whole promiscuous thing..we generally uphold people who are highly sexually active. I mean, it seems within our network, we advocate getting in with people at parties than with their partner. Not sure why, but that's the way its veiwed here. Also, from my old relationship, my partner and I both allowed each other to hookup and be sexual with other people. Simple because we said that part shouldn't just be confined within our relationship. Also, we agreed as long as we're close, always come back to each other, care, respect, tell everything and what not, we'll fit being a couple and hence getting in with others wouldn't be a problem - its just more fun

Shame that ended when she had to move interstate

I can't long distance. You may think that's just me, but a lot of my friends, and others, allow each other to go and hookup with others at parties and all.
So really I guess our group is one that doesn't seem to mind all that much lol.