Subject: Here's what I could find.
Posted on: 2020-03-08 02:29:42 UTC
It's never explicitly stated what class Okuyasu is in iirc, but it can be assumed that he's a first year like Josuke. However, Japanese classes are typically labeled by the year and then another number or letter (think class 1-A from My Hero Academia). Whether the second part of the class label means that a particular class is academically or generally better than another in real life is inconsistent, though, as far as I can find. Sometimes it's randomized, sometimes it's by name, sometimes it's by the teachers deciding who goes where, etc.
I can't find anything on what specific classes Japanese high schoolers take, but it seems like they do at least take science classes, so you could probably fudge it a bit if you wanted.
As with question two, you'd probably be fine to fudge things a bit.
That's a pretty general question, so I'll post a couple of resources. Here's one. Here's two. And here's three. Hopefully those should be enough for you to learn what you need to know. Also here's a handy chart for if you need/want to know what age is typically in what grade in Japan.
From what I can find, that would definitely be pretty unusual. There isn't much to go on for how punishments in Japanese schools work, but there seems to be at least some form of detention a student might be required to go to.
It seems like corporeal punishment was relatively rare in Japan even in 1997, so whether or not a teacher would be punished for hurting a student (and what said punishment would be) probably depends on the severity of the injury and whether or not the student in question reported it.
All in all there's not a ton of information about your questions online, but give that Jojo is an anime, you'd probably be fine to fudge a few details/throw in a couple of anime tropes if you need to to make your story work. Good luck!