1. I don't think I need to expand on the jetty answers as others have sufficiently answered it.
2. SUPing is awesome! I mean, I'm a surfer true and true but I tried SUPing about a month ago after a few years of scoffing it. As mentioned, it is fun because you can catch the smallest of waves. Additionally, I enjoy paddling out about a quarter of a mile or so and sitting on the board meditating. Very peaceful. Finally, if it's flat, at least you can still be in the water. :) I suggest trying it if you haven't done so.
3. Lifeguards are just like anyone else. Some nuts, some normal. The ones that surf are usually pretty decent though.
4. As an instructor for the AC Surf School, we spend about a half hour on the beach explaining ocean safety and surfing etiquette. I think it's why we do so well. People appreciate the knowledge and not just being thrown in the water. Why other schools don't teach these things is beyond me. They just churn out kooks that either get in the way or injure themselves and others. It's a shame really.

