First, thanks for your last comments.
The thing that you have going for you, is that the anemone is already established -- the hardest part about keeping S. Haddonis (( and really any other anemone )) is starting off with a good one. Yours appears to be relatively healthy -- would prefer the tentacles to be a bit fuller, and have it back in/on the sandbed.
Think about the lights this way (( though might be harder for you since you live in FLA )) -- If you stayed indoors all winter, and then went to the beach during the middle of July with no sunscreen you would burn-- even in a very short period of time. However, if you put on the proper amount of sunscreen you would be fine. So, think of the screening as the sunscreen -- you are allowing the anemone to get used to the increased amount of light (( actually the internal algae is getting used to the increased light, but that isn't important now )).
I have always ran the new lights their intended photo-period and at their intended height from the water. I would screen the whole tank -- won't have to worry about light spill effecting the anemone nor it moving into a spot that isn't screening and bleaching.
As for feeding, I would feed it a couple pieces of frozen (( thawed )) krill a couple time a week. But, wouldn't use more then 3-4 small ones at a time, in this case, less more often is better then more less often.