I guess the policy is whatever the mod team feels is ok.. sometimes people need another chance (I mean the site has been around for a significant percentage of some peoples' adult lives, people can change), but sometimes people don't change.
You can report a post with your suspicions and the mods will discuss it (if you haven't already and if they aren't already), sometimes it's a matter of letting the person build up a big enough pool of evidence.
I don't get too much involved in the mod stuff anymore more on the technical side.
The mod lists on the pages should be up to date (ish). There's been a few step away over time, and I don't think there's been anyone added for a while.
If you have tons of energy and want to be a mod (or know of anyone) doesn't hurt to PM the Moderator account to express an interest and then the existing mods can discuss it and see if they'd agree to propose it to Bingo.
I don't know about the other mods but I'm reaching an age where I worry about what happens to the site if I die
