Holy crap, something official. I guess there we have it, Kreia is at least 50 something...I'd still say late 60's to early 70s. Given Count Dooku was so vital and supposedly about that age range, it's hardly a stretch to say Kreia was at least as vital.
Brianna...Since she does not join a female Exile and it is canon that exile is female...I'm not so sure what bearing of significance she has...if any.
Atton has a youthful stoicism, so I'd agree there.
Visas...I dunno. Disciple, maybe maybe not, though he is mature for his age so he seems older than he actually is.
Mandalore 63? Hmm. I'd say more mid 50's at oldest.
Mira...ok I'll go for that, certainly has the attitude in her portrayal.