If your invitation says "and Guest", then yes, if not, we would prefer if it was just you.
Yes- please bring the babies! However, if you want a night to yourself, we totally understand that as well. Make sure to state on your RSVP whether they will be attending or not.
Semi-formal. We want you to be comfortable, so please don't forget to bring your dancing shoes. And if not obvious, DO NOT wear white. Or you will have 2 unhappy brides.
YES. It is limited though, so if you're able to, CARPOOL.