Hi LunaLunatic, you may want to read the latest Kickstarter post for more info, since it addresses several of your questions. Specifically, there's a bolded section marked "multiplayer," and I believe the rest of your questions are addressed in a much longer section titled "Clarifying the situation with the Steam release's age rating." We're absolutely in agreement with you regarding the Steam's age rating when you say that "this doesn't make sense," but unfortunately it wasn't our decision.
We don't have any new developments on the situation to report since that post; we're still waiting on Steam's decision regarding the game's age rating, and until that verdict comes down, our hands our tied. We can't really say anything further at the moment, due to the uncertain and tenuous nature of the situation which is still developing. Please rest assured that once we are able to say more about this situation, we will say more about this situation, and we'll have some announcements to make as well regarding our Kickstarter stretch goals and how we intend to go about fulfilling them.