For some reason I didn't realize there were two three points. Oops.

3. For NPC handling I'd probably prefer to keep it vague unless someone has a specific idea or need for one. It's less work for you and we can still cooperate and put together an NPC for a good arc or scene if necessary without making some that might not end up seeing much use at all.

Also upon review I think I agree in that there's kind of a specific anime-ey battle high school feel that I think would necessitate having later teenage-age characters. I mean, there could be some differences in how long a high school education lasts in this world, but it'd probably be stretching reality a bit to have too wide of an age gap all in the same area (especially if fighting is something that is expected)