I agree with msd2, with 1 exception (no burn intended). We also have a 55 with 4x65 JBJ system and I feel that we have a plenty of diversity. Guess it all really depends on what your ultimate goals are. At this point, just over a year and a half since set up, we are keeping 2 types of mushrooms , 3 diff. zoo colonies, green and purple/orange ricordea, a toadstool leather, a patch of GSP, 2 button polyp colonies, a bubble, a favite and 2 BTAs (the original split). If want to keep stony corals or dif. species of anemones more lighting will be required. As for us, we like the softies, seem to be easier to maintain, JMO.
We dont dose anything to the tank other than food, some occsional DTs, and, if the calc. is low, some Reef Complete by SeaChem, but most of our calc. is replaced during water changes; we are using Oceanic right now and Reef Cyrstals prior to that.
As far as fish, all I can say is choose wisely. Stay away from damsels (not including most clowns) if you can. They usually dont get along well with others. Preferably, no tangs; the tank is too small. It really depends on what YOU want, best advice I can offer is: If a particular fish strikes your fancy, reserch it before you buy it. Same goes for the corals. Everyone here will be happy to share their experiences/opinions about anything.
Good luck and much success with your reef!