blue "lobster"

I was in the LFS the other day and saw for the first time these little
blue lobsters hanging out in one of their freshwater tanks. Thinking
they would be an interesting addition to my tank, I did a little
research on them, but I have some specific questions I haven't found
answers to (didn't ask at the LFS since I don't particularly trust
their answers).

How well will one of these creatures do with other bottom dwellers?
My plecostomus is about 3 inches long so he's probably ok. The other
bottom dweller is my albino catfish, and he's only about 1 1/2". Will
he be lobster fodder? Are these novelty additions or an actual good
thing to add to a tank? I had never seen them before and I've never
seem them in anybodies home tank.

The other fish in my tank are a couple of angelfish, some red minor
tetras, and some juvenile swordtails. They hang toward the bottom at
night, should I be concerned for their safety as well?

Anybody got a pointer to a good web site for more info (I haven't been
able to find more than a couple of sentences at places I've checked).

Thanks!