On that second point, that's one of the only bad things about this game thus far in that it's extremely hard not to cheat, because the game just assumes "you must be happy as FWB with everyone" it seems.1. Equally good.
2. Not really. The only relationship that's stated to be open is only open in the sense that the partners involved agree to try threesomes, but they aren't open as in having sex with others individually.