you'll probably have to continually stock your CUC because the star will eat the crabs and snails, thats one of the main problems we have with stars at the aquarium, they will suck the living daylights out of em.
there aren't any other stars you can put in with that guy, he'd eat them... i'm not sure that you could get another CC, there are other colors of them, but i'm not 100% sure if you can get 2 CCs.... he looks good :) just don't ever expose him to the air, they are very touchy and if they hit the air the start to get sick, the are a lil different than the west coast seastars that can be outta water....
also, if you see him upside down for more than a few hours, you'll need to help him over. they can get stuck upside down and die. thats what happened to my sisters