Envelope Etiquette

I've run into more etiquette questions/issues with the invitations (specifically, the outer envelopes) than anything else so far. Since I am probably not the only one who doesn't have these rules memorized, I thought I'd share my findings on here:

1) 'and' vs. ampersand (as in Mr. and Mrs. John Smith vs. Mr. & Mrs. John Smith)? Writing out 'and' wins. Sucks for us since we've already printed 60 envelopes with '&'!

2) Separated or divorced guests? One of our guests is recently separated from her husband and with such a delicate situation, we didn't know whether or not to use Mrs., Ms. or her maiden name on the invitation. Since I couldn't find any hard and fast rule for this one, I decided to just ask her what she prefers. She opted for Ms. (first) (married name). I think if you are close enough to the person, asking their preference is the way to go.

3) printing vs. calligraphy? Of course calligraphy (or addressing the envelopes yourself) still wins, but we decided to throw this rule out the window due to time constraints and lack of extra $ to hire a calligrapher. Plus, I think the last 5 or 6 wedding invitations I've gotten in the mail were printed, and I didn't even think about it, so I'm hoping no one will notice!

4) If printing addresses on the envelope, should the font match the font used on the invitation or be some sort of formal script font? I found contradicting opinions on this but since there were a few posts/articles stating that it was acceptable to use the same font on the outer envelopes that was used for the invitation, we decided to go with that -- it looked better for the style and feel of our particular invitations.

5) Street vs. St./Apartment vs. Apt., etc.? This rule is pretty clear cut, always write out the words--> Street, Avenue, Apartment, etc.

In the end, we have decided to just breathe and do the best we can because there are too many rules to keep up with! We want to be respectful of our guests first and foremost -- and upon receiving their invitation in the mail, I really hope that they will just feel excited about sharing in our special day rather than focusing in on the fact that we printed out their address or slipped in an '&' instead of an 'and'!

Were there any invitation etiquette rules you decided to throw out? Did you experience any backlash from family or friends as a result?