"She has great respect for her teacher."
Translation:Elle a un grand respect pour son professeur.
"Professeur" does not have to be only a university-level teacher. As Sitesurf explained on another thread, "in France, professeur is used for all teachers teaching one specific discipline (as opposed to primary school teachers)...[and] 'enseignant/e' is used as the generic job of teaching.". So it is not wrong to use "professeur" here, but "enseignant" should certainly be accepted.
I must leave the "envers"/"pour" question for someone more fluent than I, but I do know that it is "son professeur" because the word "professeur" is masculine.
Unlike in English, the possessive does not relate back to the possessor, but to the thing possessed:
his book = son livre
her book = son livre
his table = sa table
her table = sa table