Re: Miss when addressing a teacher? / Name or last name?
I confess I am always a little taken aback for a moment when I hear a student referring to a teacher by his or her first name. However, we certainly don't use "Miss" or "Sir" in a public school.
Younger students might refer to a substitute teacher (whose name they have forgotten) as "Teacher" though usually the sub will write his/her name on the board.
Older children who need to address the substitute teacher will probably say something like "Excuse me, Mr... uh... Mr..." and the teacher will helpfully supply his name, rather than saying "Excuse me, teacher."
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.