re: As an adult, do you refer to your childhood friends’ parents as Mr./Mrs. [last name]?

It varies. Some parents are more or less friends as adults and get the first name treatment. Some parents for a variety of reasons will always be Mr./Mrs. Last Name.

On a related note, you know you’re getting old when kids at duck camp start referring to you as Mr. First Name. It’s a real “when the frick did that start” moment.