1. If the outer envelope says "Mr. and Mrs. James Jones," does the inner envelope have to say "Mr. and Mrs. Jones"? I feel a little weird not including the woman's first name anywhere, as though she may think I don't know it (for FMIL's friends, etc.). Can I use "Mrs. Joanne Jones and Mr. James Jones" on the inner envelope, or stick to tradition?
2. On my STDs, I addressed a few people (3 I think) as "Dr." when they have a PhD but no MD. I later learned that PhDs don't get addressed as "Dr." on social correspondence. Should I change it to "Mr."/"Mrs." on the invitations now, or keep my error consistent and address them as "Dr."?
[Edited for grammar.]