According to the "Best Hawaiian Language Workshop" (refer to the link, below),
"Mister" is "kane" (pronounced KAH-neh)
and "Mrs" is "wahine" (pronounced wah-HEE-neh).
Mr and Mrs
Mr and Mrs is correct or Mrs and Mr is correct
Mr. and Mrs. (ex. "Hello, Mr. and Mrs. Evans" instead of "Hello, Mrs. and Mr. Evans")
Mr. & Mrs. Smith
In the US it is normally Mr. and Mrs.
Dr. and Mrs. or Mr. and Dr.
This term is not used, really. One may say Wahine after the name (for example; Mrs Smith.... Kamika Wahine)
I would address it to Mr and Mrs David Keys. For the salutation I would use Dear Mr and Mrs Keys.
Mr. used to be acceptable to address a household by just using the last name, e.g. "Mr. Jones". In modern times, it is typically to use "Mr. and Mrs. Jones" or "Mr. and Mrs. Timothy Jones".
Mr and Mrs its just more formal today in society.
"Mr" = "Herr". "Mrs" = "Fru".
mr ans miss or.... for mrs is madame. mr ans miss or.... for mrs is madame.