#1 - clown/anemone, pistol shrimp/goby, acropora/acropora crab, most fish/cleaner shrimp or cleaner gobies
#2 - parasitic isopods, zoanthid eating nudibranchs, red bugs (eat SPS), anything that lives on another organism that benefits itself while hurting the organism it lives on
#3 - Soft corals, no skeleton with large polyps, get most food from zooxanthellae, though some are non photosynthetic, such as tubastrea and dendrophyllia species.
Stony corals, have skeletons, and the polyps can retract into the corralite(part of the skeleton that the polyp retracts into). They are divided into small-polyped-stonies(SPS), which are the ones that look like dead trees or plates. They have more skeleton than polyp, and the polyps themselves look like little tiny flowers. Then there are large-polyped-stonies(LPS), which usually have a tube like corralite, and a very large polyp. Both rely greatly on light, but will grow much faster if they eat.
#4 - Just a list: Acropora, Montipora, Yellow tang, Regal blue tang, Ocellaris clownfish, lots and lots of stuff to list...