That depends on how you treat them. If you treat your boss like your mate, that's how you write to them, but I would suggest that you don't try it!
"He was your first boss" if you are writing/speaking in past tense, like telling a story. "He is your first boss" if you are writing in future tense, like writing a guide/walkthrough. If the person is still alive, you would not be incorrect in saying "He is my first boss." If you say "He was..." it might be presumed he is no longer among the living. It is not unusual to hear your boss' boss called your second boss. That would make your immediate boss your first boss.
Refer him to your boss, in writing, and ask for an answer in writing.
The singular possessive form is classmate's.
The proper way to address a female boss in writing is to use Dear Miss and then the name. If she is married then use Ms. or Mrs. instead.
The cast of Connect - 2013 includes: Vachik Adamyan as Classmate Anna Bahen as Classmate Chris Bealer as Classmate Malia Corpuz as Classmate Kellen Ford as Ryan Jessica Gaitan as Classmate Vartan Kyupelyan as Classmate Kallayah Logan as Classmate Brandon Muschcoilz as Classmate Lauren Reel as Classmate Ansley Rowell as Classmate Danny Sedrakyan as Classmate Tai Urban as Classmate Elisabeth Van Stralen as Lisa
The cast of The History Fair - 2013 includes: Jo Anne Sennett as Wife Jayden Asay as Classmate Harrison Bontrager as Classmate Rachel Boyle as Classmate Glenn Bundy as Husband Alec Gainey as Classmate Madison Hales as Classmate Bryan House as Mr. Gosser Brookelyn Hughes as Lily McKenzie Jacobs as Classmate Doug Lemon as Man Natalie Lindquist as Classmate Nicholas Lowman as Classmate Sydney McGurn as Classmate Jada Reffitt as Classmate Tara Rusinack as Classmate Graycee Sands as Classmate Wyatt Stiffler as Classmate Ciara Stout as Classmate
The possessive form for the singular noun classmate is classmate's.example: I borrowed my classmate's notes for the day I was absent.
Like a boss
Yes it is.
No, it is not. A classmate is a person, a noun.
I hate my new classmate "Andrew" he is a bully to me.
bad