1. Bristle worm - good for the tank, bad to touch (the bristles get stuck on your fingers and it can be painful).
2. Valonia (bubble algae) remove now or regret later. Some people don't mind it, others detest it. It can be a problem down the road so best to get on it early, IMO
3. Foraminiferans. I forget the specific name, they're harmless filter feeders and very pretty color
4. Serpulid polychates. Basically a type of worm with a fan for a mouth. harm and "neat" to watch.
5. your guess is as good as mine. i'm not sure what those are, they could be xenia or hydroids or a host of other things. keep an eye on them as they get bigger, they could be good or bad. Maybe someone else knows what they are?
For more hitchhiker info try here:
http://www.xtalworld.com/Aquarium/hitchfaq.htm