1. Will the tank support the anemone without overloading the bio mass?
2. I notice some of the anemones require "strong" lighting meaning how many watts and what type of light? I currently have a 15W Actinic light (however, i think that its not enough)
3. If i do need more lighting, how can i upgrade it. Do i need to get a different ballast, light or new hood.
Well, my preference at this point would be to try to talk you out of getting any anemone, why? Tank size.
2 posters one with a 10 and 20 gallon tank the other with a 5 gallon tank. Why talk you out of it? Stability and water quality. Bad things can happen in any tank but they happen much faster in smaller nano sized tanks. Keep in mind that your water volume goes down with rocks and sand.
One requirement, or two, of an anemone is stability and water quality. This is better achieved in larger tanks say 55 gallon or better.
15 watts of lights would spell death to all but the pest anemones and even they might not survive that. My preference is VHO lighting of at least 4+ watts per gallon for the less light requiring anemone like E. Quads = BTA or bubble tip anemones.
VHO, PC and MH all require special ballests to run the bulbs, Ice Cap ballests are a favorite. MH lighting is a must for tanks 18 inches or deeper as they are able to penitrate that deep, this is important for sand substrate anemones like LTA's or Sebaes.
My best advice is steer clear of anemnes in less than a 29 or 30 gallon tank. Does that mean some folks haven;t tried? NO. Does that mean you can't do it? NO. Some folks get away with it, but many don't talk about their failures.
Its your tank and your choice - favorite Broomerisum*