In general terms, it sounds good, Nelson, we can try that.
(I'm unsure about the need for a specific mentoring system for new admins, Daniel, sorry)
If we want to try a more flexible system for rating proposals with optional comments, etc. (instead of just voting "yes/no"), we can "dogfood" the new "Rating System" ( http://doc.tiki.org/Rating#Users_ratings_in_Forums ) in a new Forum devoted to this system for Admin Teams (public). One new thread for a new proposal of a Admin Team member.
So that others can review the system freely, be aware of he evolution, propose other members for the next round, etc., while keeping the rating choice of each user hidden (show just the resulting table)