I did not know about this site until a little over a year ago. I once wrote a humorous overview of our efforts at choosing schools for UG. My D only auditioned for 3 VP schools (but some MT programs too). She never did a summer program. And I never knew about summer “festivals” until sophomore year of college.
For VP you can start late - and maybe jazz is the same. Others can comment on that. And when he gets to college…don’t worry…he’ll find and be accepted to expensive summer programs/festivals too.
As for studio assignments, my D got an offer, we thought great! Never did a lesson with her. I never understood you were suppose to research it.
Hopefully others can clue you into the jazz world. You are asking good questions. But really your son is fine. Not everyone knows all of this “stuff” - I certainly did not!
BTW - a studio is run by your private lesson teacher. It usually meets once a week and students perform for each other and critique each other. All the students have the same teacher for private lessons weekly. So the studio typically becomes tight. Generally there are different age groups in the studio. So whomever his private teacher is, that will be the studio head. Of course jazz teachers may run studios differently but this is the general idea. He may want to contact the school to ask about how he would get a teacher (or studio assignment ) if that has not been done yet. Schools do this differently.