Seems this'll mostly be a recap, since the questions have been fairly thoroughly answered, but I'd like to toss in my two cents.
Foxfaces, like all rabbitfish, have hollow spines in the dorsal and ventral fins, and can inject a powerful venom. The venom is a heat labile protein, which means heat will break it down. I've heard it is extremely painful, but then I've never been stung, and he's even brushed my arm with spines extended. I even pet his nose once while feeding him. As with any puncture occurring in a marine environment, heat, then doctor for antibiotics and tetanus. This is an extremely rare occurrence. Google it, and you'll have trouble finding stories of anyone being stung by a rabbitfish. They're just too timid.
The mandarin dragonet (not a goby. Who started that? Seriously! lol) is an extremely difficult fish to care for. There are some wonderful threads on this site, and articles all over, but the short version is that this fish is best left on the reef unless you are willing to pour a lot of time, effort, and money into feeding it. Sucks because they're so beautiful!
And to ObscureReef's question: Bubble algae doesn't really look like bubble coral. The foxfaces just graze all day on anything green they can find, but mine has never shown any interest at all in my corals, and I have soft, LPS
, and even some montis. Like most marine herbivores, they turn to meat when very hungry, but seem to be less inclined than most to do so. Mine LOVES caleurpa. I mean, it's like giving spaghetti to a starving child. He practically slurps it down! Chew, stupid fish, chew!