Re: Salutation question
I usually look for sites that have to do with weddings and wedding invitations for questions like this. They have lists of how to address envelopes to every type of couple imaginable, from married couples with different last names to same-sex couples to members of Congress married to royalty... okay, well, maybe not royalty. But virtually every other combination.
If you're not convinced about the above answer (though it looks exactly right to me!), google around for "addressing wedding invitations" and see what you find.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.