Tangental

@Gibbeynator

From what I'm told, you can still get all the endings only playing single player, you just have to do all/most of the side-quest type stuff.

@Dizazter
Profits are rarely much unless you're working at a publisher, and then you usually don't get a cut.
Bonuses can be tied to that stuff some times though, which can be nice if your studio does fantastic ... but again that's pretty rare.