You have a very strong profile, and your odds are good, especially if you have talked with the diving coach and have their support.
You should be very thoughtful and intentional about how diving is going to fit into your high school life. If you think you may want to dive in college, access to coaching and training time will be a big factor. The day option really may be your best as you can stay with your current coach and keep your rides to practice. Make sure that schedules and time for study will allow this. Before you add schools, make sure they can accommodate this aspect.
This may not be applicable; schools usually only care about AP scores for evaluation or placement purposes. I think students are only allowed to take AP exams during high school, including the exam period before 9th grade, with only AP World Language exams being the exception. I could be wrong, however.
A school cannot offer an AP course in 8th grade - except world language. An 8th grader can take AP courses at the HS where possible, which is what I did. They can also take the exams by self-studying, with the typical caveat that they need to find a test center that would register them as an outside exam-only student.
You’re a strong candidate. Both schools have good swim teams. PA is excellent and the overall swim team culture/community is strong. Make sure to reach out to coaches because they will have a lot of (positive in your case) influence in the decision.
Make sure to go to the Open Houses and talk to the coaches in person there. Exeter does a phenomenal job in their Open Houses. PA less so, but much better revisit after you get in.
How many kids from your school go to these places? Familiarity with the school is helpful from an admissions standpoint.
Perhaps the most important consideration for you is whether you want to board or not. People don’t talk about it enough, but “Day Studs” have a different experience.
Selling against my own trade, but I feel that the boarding experience is a critical part of the “prep” of these Prep Schools, so that’s a benefit Exeter affords you that PA won’t. Plus, Exeter is awesome in any case.
This really is key. Boarding and participating in a sport at an elite club level is enormously challenging. Doable? At some schools and in some sports, but this is probably where the OP needs to do a deeper dive, both into what is possible at each school and what their goals are.
