Yes, it's proper to use an ampersand in a salutation and it's been high etiquette for centuries. So, it should be: Mr. & Mrs. Smith. There are many styles of ampersands and Caligraphers often create the more unusual ones, but the above is the most common and just as acceptable.
Dear Judge Smith and Mr. Smith.
yes
EdD indicates a doctorate degree. Proper salutaion would be "Dear Doctor xxxxx:"
The proper salutation to more than one doctor would be "Dear Doctors". A person can also list each doctor's last name after the word doctor. So if the names were Smith, Jones, and Arnold, the salutation would be "Dear Doctors, Smith, Jones, and Arnold".
Dear Mr. John and Rev. Sally Smith,
Dear Judge Smith: See http://www.factmonster.com/ipka/A0771340.html for more info.
Retired or not, the proper formal salutation should read: Honorable Walter K Smith Dear Sir:
The envelope would be addressed as: The Honorable John Smith United States Senate Washington D. C. 20515 In letter: Dear Senator, or Dear Senator Smith
Dear Mr./Dear Ms. followed by their surname.
Dear Smith's
The letter salutation is written as: Dear Doctor and Judge Smith. The envelope is written as: Doctor Adam Smith and the Honorable Eve Smith.
Dear Counselors: