Is the fixture I posted above the same one you have? If so, I would not add any coral. I was thinking that the fixture you said you have has 2x36w T5 HO
from your description, but now that I see there is no HO
in the description thanks to melosu and that it is just 2x18w, I now think that it is not good for any coral. I would stay with fowlr
until you feel comfortable to move onto reef, then get the nova extreme pro.
Do you have test kits, a refractometer, or thermometer?
You should be fine with just the rock if you seed what you have in there now with live rock.
Hope this helps.