Not that I'm considering it (I'm far too young) but how would you become a moderator?
And how many posts must you make to go up the ranks (Newbie, Truth Seeker, Advanced Student etc)?
You become a moderator at the discretion of the site administration. It's an invitation sort of deal. As for post count, I'm not sure.
As Sera said, it's by invite based on good, helpful and intelligent behavior on the boards. The staff, in the past when we've needed more mods, have all made suggestions as to who would be good from the memberlist and why. Then we all vote and if the new person is accepted, we ask them if they'd like to be a mod.
As for the ranks, it goes like this:
0-24 posts = newbie
25-49 = truth seeker
50-99 = student
100-249 = advanced student
250-499 = tutor
500-999 = professor
1000-1999 = master
2000+ = guru