One thing not mentiond, the different species of clownfish do have thier differences
the maroons are a bit larger and slightly more aggresssive than some other species.
The most common are probably the false perculas( or oscelleris) and perculas, which are more docile and smaller as well are also easier to keep in many cases. Esp the oscelleris.
The most aggressive, IMO is probably the tomato which gets fairly large too. Where as the sebae is another more desirable, being less aggressive than some others.
If getting clownfish, you should consider getting only one spcies in each tank, but most of them will do fine with others of their own kind. A little research on brokynella(sp?) a.k.a. clwnfish disease is something we should do as well, before getting clownfish. Not always a problem, but when it is, it is generally lethal.
Tehir diet is nto too difficult to maintain, clownfish are omnivores and eat pretty much anything you would feed. Brine, mysid, algae, flake and pellet foods consisting of vegetataion and meat is generally all that is needed. Ours also likes blood worms.