Actually, there's a little community of new people forming on the server. They clearly want to make the server populated. I think they'd like it if you'd help them with that by playing/inviting people.
TL;DR: Join, there's players that need friends!
1. Only Chew would know, I think. It would be a very long time, though, since I've passed by abandoned towns many times with no visible change.
2. There was a poll about if griefing/looting should be bannable, but I don't remember if it was super conclusive. I'd say you just shouldn't do it...