nissan, since you are in florida, i highly suggest you try roggers food. it doesnt breakup and leave particles everywhere in your tank. attach it to a clip and let the fishes nip at it. keeps them busy for 2-3 hours
i would not do a harlequin shrimp for you. you would need a good supply of starfishes and its more for experts. later on, you should be fine getting one once you've read up on it
your t5 set up is much better than the marine land unit. if you want nicer leds, check out evolution LED. theyll be the cheapest you can find thatll sustain corals. the marineland unit is only for softies and IMO its a big waste of money. creates very little par unles you measure directly under...
i wouldnt have melev make the sump, he's overpriced LOL. melev has become a brand name in this hobby.
if you can find someone close by, thatd be your best bet. do you have a local forum or MAS society close by?
if im not mistakened, these lights do not have curved parabolic reflectors or individual reflectors for each bulb. therefor the light really isnt strong enough for anemones. as for the options, im not sure what you're talking about.
for your sump, i would either do diy or invest in someone making one for you. check out melevs sump designs and see what would suit you more and design according to that
if its mh on good reflectors or good leds, then the 4" would be no issue really. at the bottom you should only see a differece of ~50 par. as for the dimensions, id prefer more shallow and deeper than taller and leaner.