This should be really easy to implement: on the "Classmate Profiles" page, there is a 'radio button' to select (*)A-Z -- but that sorts only by lastname. How about another button for A-Z Firstname ?

I strongly disagree with this suggestion. I feel a second button for A-Z Firstname would make it confusing for classmates and be of limited usefulness.

Right now, selecting "A-Z" results in a list ordered by the last name the classmate had in high school, i.e. the maiden name for females, which is very useful. The married last name is in parentheses.

Could make sense in non-English areas. But yeah, limited usefulness in the USA.