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.
In fanfiction, chibi Naruto can be best characterized as a ball of sunshine. He's constantly chasing after his dreams, whether it's to be the best ninja or to get a bowl of ramen. He's not afraid to speak his mind and is very straightforward. His emotions are always on his sleeve. Chibi Sasuke is the opposite in some ways. He's reserved and a bit aloof. He values his alone time but deep down he's also lonely. When it comes to his relationship with chibi Naruto, he's slowly learning to open up. He's still competitive but in a more innocent, childish way. He's the type that will secretly admire Naruto's courage even if he doesn't say it out loud.
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.