So last time I just went all BoS and didn't even try to join anything (except MM which I basically ignored). However this time around I'd like to do some of the side quests for Bos, and RR and maybe even the Institute. Do I have to actually 'join' these factions to get the quests ... and then later choose the one I wish to finish the game with, or can I just volunteer to do their quests? Does joining one (say RR) mean I can't join another (say Institute)?

Thanks.

I joined all of them my first time through..I'm pretty sure you have to agree to aiding them to get the side quests..I think later some may clash and piss off other factions, not for certain on that..I only did a few for each then proceeded to the end with the institute..now I'm going to try the BoS ending.

Well my idea is to join the BoS if that is required to do some of their side-quests, then join the RR and so some of theirs (I read that theirs actually run out), course the whole time doing errands for the MM. I suppose at some point I have to pick one to build a teleporter with, then maybe do some quests for the Institute? Seriously though if I join everyone where is the point of no return where I have to stick with one till the end?