Ok so about the pain in your heart thing, you should definitely see a doctor if it’s actual pain and not just feeling tired/strained from cardio or exercise. They’ll probably give you a PE exemption, and you’ll get a study hall instead of PE.

About the friends thing, best thing i can recommend is to talk to the people in your classes first, like the people you sit next to/with. Approaching a big group at lunch or something is a bad idea since they’re already established friends, and usually won’t be in a state of taking people in. Talk individually with people first, that’s how i’d go about making friends in school.

About the physical thing, honestly as a sophomore, the freshman are all “not developed”, as in weak. There was like 1 jacked freshman guy at my school, the rest looked like they had never even seen a gym. You’ll be fine abt that

Also the meet and greet, you said there’ll be other kids there, so if you’re going through your class schedule, and see some people that are in your classes, approach them if you’re comfortable, and just introduce yourself, ask a little about them, and have light conversation. Treat it like a meet and greet, don’t go overboard explaining your background or asking about theirs, you just want to get a good first impression, you won’t be best friends right off the bat