Tox has a work-in-progress protocol feature called NGC (new group chats) that could add moderation to groups.
I'm not sure about grouping of groups - that can be done in UI in clients already, but having shared permissions would be an option (once 1. is implemented)
This is entirely a client feature. Toxcore has no concept of history, it's purely a network library. qTox has encrypted chat history with search now.
Here are some design ideas:
Stickers+Reactions, bots and other features are not necessary, but No1~No3 are the big ones.