First of all I've never been in a poly relationship and I've never been in an R/L D/s relationship. While I can't really answer Q's questions I can give you all a nice little monolog about my thoughts on the subject. I can be VERY needy and jealous... but I can also be fairly open minded (or atleast I like to think I can be...)
I've been 'one of the guys' for most of my life, in several different groups. I inevitably end up developing a crush on one of the guys when that happens I'm generaly amused by the blond bimbos that they crush on and want to sleep with and feel the need to tell me all about But when my friend(s) develop crushs on the guy of my lust then I get incredibly jealous even when said male has no interest in said friend.
On the other hand I've sent old boyfriends (when we were going out...) off to varrious strip clubs and such.

Another thing to consider... When my first boyfriend was deployed I spent alot of time hanging out with a guy I went to school (who was also the boytoys half brother) and basicly everyone thought that the brother and I were involved. We did all of the things that your typical teenage couple do except for the sex stuff. Same thing when I was dating a guy who was in South Africa...

Pretty much it all depends on the people involved. and how secure they are in their relationship.