He was a Pistol shrimp. A good guy (at least not a bad one). The one with the evil eyes is the bad one.
If you have another back tipped crab leave him out of the tank.
Worms... Hmmm. Look up Eunicide worm and see if that looks like your red/brown guy. Those are typically not good.
This was mine:
The bristle... again if you can't post pics of him do a search for bristle worms and see if you can ID
the one you've got. I liked mine. Up until he bit my shroom. Pulled the worm and the shroom recovered (is about to split, for that matter).
Take a look at the top of the ID
forum for the common hitch hiker guide. You might find your answers there. Some of the worms are beneficial (spaghetti, etc) so I wouldn't throw all the babies out with the bath water!