Although dwarf lionfish tend to have small mouths, that doesn't rule out the possibility of it trying to swallow the coral beauty or damsels (unless you get a fairly large one i.e. adult). Many angels also have a tendency to nip the long rays of lionfish so that is why I say "iffy." Choose wisely if you go this route
Scott is correct in that dwarf lions and many of their larger counterparts will perch within the liverock, which is why anemones of any sort are usually passed upon. Most snails should do fine with the eel (just make sure to stick train it) and possibly cleaner shrimp if the lionfish/eel accepts them for their cleaning abilities rather than an easy meal.