It's hard to say I wouldn't do that unless I was sure the guy friend had no feelings towards me. I've done that before and it didn't end well since he liked me and I don't really have any guy friends that don't at least like me somewhat.
1) Yes, I've done it several times. My guy friend and I are really close and both physically affectionate. Plus, my significant other and I live a few hours away from each other, so we don't get to be physically close very often. He knows my guy friend and I sleep in the same bed sometimes, and he doesn't mind. I know he has slept on couches with his close friends, and I'm okay with it. My significant other and I have very strong trust. Some boyfriends/girlfriends may not approve, depending on the relationship.
2) We definitely cuddle, not even just when sleeping.
3) I usually wear sleep clothes (shirt, shorts), but also a bra. That's the one key difference. Sometimes I'll unhook it for comfort, but it's still on there.
4) No, I wouldn't be mad. Especially while sleeping, that's not his fault! But even while awake, whatever, it's fine. I think if you are close, you can tell from his body language if it was unintentional--or if he's hoping you'll notice. My guy friend would probably just shift away for a bit and hope I wasn't aware.
2)I cuddle with my female best friend, but I doubt I would with a male friend..I do hug my guy friends a ton, but for some reason, cuddling in bed with a guy friend is a little inappropriate in my eyes..just because a bed is involved..but if I woke up and he was cuddling me, I'd feel bad waking him up to get him off me
3)PJs..normally I sleep nude or in panties, boxers, or (at most) a nightie, but if I have male company over (aside from my bf) I wear PJs.
4)If he had an erection, I'd feel too awkward to be mad..though I'd definitely shy away from him and I'd probably end up sleeping on the floor or couch