Sure!
Secondaries are obtained automatically after 45 IC posts and six weeks of membership. That is, once you've been a member for at least six weeks and you've made forty-five IC posts, you can simply make your secondary character's account and join! No need to ask anyone for permission or anything. ;> If you've been very active, you
can request a secondary character evaluation before you complete both the requirements.
Auxiliary characters (third, fourth, fifth, etc.) are by request. After four weeks have passed since your last character request (e.g., if you pick up your second, you then wait a month to request your third) OR two weeks have passed since you dropped a character (e.g., you kill off your third character and want a new third character), you can post a request for your new character here; PM one of the 'SA members or the 'SA account itself; or you can prod one of us 'SA people over IM to get to you. :>
We evaluate your activity on a basis of about a month and a half, further back if there's doubts about how active you've been. We look for a 3:2 ratio between your primary and auxiliary characters -- so if you have two characters and you make 12 posts in a week with your primary character, we'd ideally like to see 8 posts with your second character. We also evaluate consistency -- e.g., if you're keeping up regularly or if you have long stretches of down-time between replies, but those things aren't as important as your ratio + post count. :3
All of this is expanded upon/outlined in the
Procedures topic, but there's not a lot there that I haven't covered here. :3 I hope that answers your questions!
Let me know if you have any others.
Edit: LAWL SHADOWPOSTERS. :|