Help with 1 week old 10g nano

[Der_Iron_Chef]

The hermit crabs should be fine. The organisms in the last few pictures look like some sort of worm (like a Spionid worm) and are reef-safe. The "shrimp looking things" sound like amphipods and/or copepods, though hard to say without a photo. They are also reef-safe.

Hitchhiker starfish can be bothersome, but I'm no expert on starfish, so I'll leave that to someone else who actually knows something