So how do I get into one of these Societies?

In order to join a society, there is no one on the BB from whom you need "permission"!  Simply post a message stating your desire to become a member, and then choose a number and a function.  Functions can be virtually anything that strikes your fancy (within PG limits ;)).  Numbers can also be anything you want: they are not in any kind of order within the societies, and can be random, of personal meaning, or chosen simply because "they look nice".  Each character's Society-list page includes links to complete listings of each society's members, their self-assigned numbers, and the jobs the "Title Fairy" has inspired them to take on.

In between updates (or if the page is incomplete), however, the best way to double-check that neither your number nor your intended function, if you've chosen one, is already taken is to post a question to that effect to the BB.  Someone on the board  will get back to you -- people on the SAJV BB are extremely friendly, and always answer as promptly as RL allows.

And -- all of Phileas' assertions and fear to the contrary -- I assure you, we don't bite!  ;-)