Toge Inumaki is important too. His special cursed speech ability makes him stand out. Also, the principal of the school, Masamichi Yaga, is likely to be important as he is in a position of authority and has an influence on Gojo and the other students. There could be other characters like the members of different clans that also play roles in the complex web of the story.
Sure. There was an artist who specialized in creating PFPs with a surreal and dreamy style. One of his PFPs got shared by a major digital art collector on a popular art platform. This led to a flood of requests for his work. He was able to sell many of his PFPs as limited - edition digital art pieces and made a name for himself in the digital art community.
It's hard to pinpoint exactly where Gojo is at any given time in the manga. His whereabouts change as the story progresses and different scenarios unfold. It could be in a supernatural realm, a mission site, or interacting with other characters.