I would make some changes to the fish selection you have chose. First off anthias are schooling fish. Without a school, they stress and hide. 9 chances out of 10 you wont ever see him because he'll be hiding behind the rocks. They are als active swimmers in a school so they would need a tank of at least 75 gallons. I tried 3 in my 55 once and they still stressed out because of to little swimming room. They are also delicate and suseptible to ick and other issues due to stressing so easily.
As for the mandarin. I would avoid at all costs. They needs a tank of at least 75 gallons that has been set up for over a year unless you buy copepods to feed them. Most of the time they will not eat flake, brine or mysis shrimp. (brine shrimp asctually has little nutritinal value) If you do get one that does eat these foods, it will do fine for a while then slowly waste away as these foods do not have their needed diet requirements. These are hard fish to keep and most end up starving to death especially in a new or small aquarium.
Remeber, damsels are aggressive, especially in schools. While they are super hardy, they tend to pick on the smaller fish. With a tank fo this size, you will need to go with the more docile smaller fish. Chromis tend to be more docile and accepting of tank mates.
If you get a dwarf angel remeber that they too are territorial. If you get one, add him last after everyone else has selected their parts of the tank. Its no fun trying to rearrange a tank because of an aggressive angel!
Although bright and colorful, I would also avoid yellow tangs. They are extremly active swimmers and get stressed in a confined tank. This can lead to issues like lateral line disease and a variety of other diseases. The last thing you want is a tank breakout!
As for equipment, it is my belief that protein skimmers are mandatory to hold the bio-load of a reef tank. Another not necessary item but very benneficial is a UV steralizer. You dont need a large one for that tank size so you don't have to spend an arm and a leg. This will help if you do get an outbreak of ick or any other disease or parasite. I run these only when the tank is in an outbreak as it will kill the phytoplankton in the water. Since you cant really treat ich aggressivly in a reef tank without killing the corals and algae, these are definatly helpful. I would avoid canister filters like a fluval. These end up being nitrate traps. The debris gets caught in the media and then sits and rots until you clean it out. The water still gets cycled through this debris and thus it is basically still in the tank releasing these chemicals. Look into a fluidized bed filter. These are easy to use, cheap on the budget and work well.
If you get RO water, you will have to buff up the alkalinity and the PH to satisfactory reef tank levels. Personally I have always run tap water without a problem and now run the well water at my house. It really depends on where you live what all is in the water.
As long as you arnt planning on doing a lot of stony corals and clams, you will be fine with not getting a metal halide. Coralife has a great little light fixture with an actinic,10000k and lunar lights in it for a decent price. (about $160) If you do specifically want those corals, you will need more aggressive lighting.
Hope this helps!
