May I just add that some of the fish you are buying (of the tang species) are the most susceptible to ich. After the 6 week period of tank going fallow, I would recommend a better starter fish, something more hardy than a tang. Good beginner fish are hawkfish, damsels, basslets, certain clownfish (preferably captive-bred), blennies, gobies, cardinalfish, banded lizardfish, maybe a small puffer like a valentini or white spotted, or maybe even a foxface.
I would recommend STAYING AWAY from all angelfish, all butterflyfish, Pipefish, Seahorses, Long-nosed Filefish, Blue Ribbon Eels, Stonefish, and Moorish Idols. Mandarin fish should also be avoided in non-reef tanks (they are hard to feed) and tangs for a short time - add them later when tank is WELL established.
Its tough to stay away from all those great looking fish, but it will save a lot of headache and cash flying out of your wallet.
Good luck and hang in there!!!