I dont think the cat has to require a new character or new account, more so just interacting with them.

I'm thinking of a category that involves getting all (or most) datacrons either on a certain world (as an IL sort of) or on a certain side. Of course, some of them require outside help so there could maybe be a solo category for the solo only ones and a cat for all of them, but its just a thought anyway.

Not for ILs, but for fullgame yes

All skulls are allowed, however I believe Acrophobia is not.