Aragonite sand is best although you can use a silica sand. The aragonite sand will slowly dissolve and help keep your alkalinity stable. You can get live sand, but any sand you put in a tank with LR
will eventually become LS
If you go with a shallow sand bed (about 1"), you'll want to siphon it carefully. It will go through the gravel vac...or some of it will. If you go with a deep sand bed, you won't want to siphon it at all. If you do, you'll disturb the anoxic areas in the sandbed which defeats the purpose of having it.
The filter media isn't needed if you add 1.5-2lbs of LR
per gallon...70-90lbs in your case. The LR
is the bio filter. If you use external bio media, it will produce nitrates which you don't want in the tank. For more info, go to the "articles" link on the left side of the home page. Read the articles on curing LR
and the Berlin system of reef filtration. What kind of filtration you use depends on what kind of tank you want to have.
I also recommend reading "The Concientious Marine Aquarist" by Robert M. Fenner. I have this book available at http://www.captiveraisedcorals.com/Books.htm
or any online retailer that sells books should have it as well. I'd shop for the best price, but it is full of info that will help you very much.