Bront: Welcome back! To address your points
1) Regarding Vanitri, I have emails saying he's been approved for L10. I can forward them to you, if you want.
I never saw a cohort, and Vanitri hasn't really been active. I think it's acceptable to swap out Leadership. Maybe make a proposal about it?
2) A) There are a fair few, very young L1's, and a decent, high level party, average L8. I don't know how active their players are, though. It's been a long time since they've gotten any attention.
B) I played Fimble as an NPC for a while. I didn't give him any time XP while he was being NPC'd, but you could probably convince me (as a judge) that NPC Vanitri deserves some time XP.
You should know, though, that NPC'ing Fimble and keeping him out of the spotlight caused me to fall out of love with him and eventually officially retire him as a PC. So, NPC Vanitri at your own risk!