1) I think I would define it as an unusually high number of sexual partners during a particular timespan. I'm going to go with more than a couple a month or so with the caveat that I may revise that at any time.
2) No, not in itself. Cheating is bad, so is letting yourself be used but if everyone involved is up-front with what they expect and use safety, there's nothing wrong with it at all. I think we complicate sex far more than we need to and we shouldn't feel bad about sharing our body with someone for no other reason than having fun, so long as everyone is honest about what they expect.
3) I tend not to use the term at all. I used to call my promiscuous friends (male and female) "slut" in an affectionate sense but I've stopped doing that now because some people misunderstood that it was meant in jest and I don't want to hurt their feelings.
4) I'm a Luciferian Satanist. My faith doesn't have much to say about the act of sex (other than being careful of the feelings of others and yourself) so no.
5) Quantatative.
6) Not that I can think of.
7) For me personally, it tends to although how much intimacy it creates varies wildly.
8) In theory, yes but I've never done so.
9) Sure but, as a guy, that's rarer. You know how women have those really close friends that you can talk about all your feelings with? Guys don't get those. Our friendships can be as close but they tend not to have the same explicit discussion of intimacy.
10) Not that I'm aware of.