you want to put in about 2 inches of live sand..(so ive been told) which is usually equivalant to the gallon ratio. (1 gallon = 1 lb of live sand)
Live rock on the other hand ive heard (1 gallon = 1 lb of live rock, also 1 gallon = 1 1/2 - 1 3/4 lbs of live rock.) I personally live by the 1 lb to one gallon rule on both.
As far as the different kinds of live rocks.. I think its personally user preference.. i have 3 different kinds in my tank lol. Fiji is usually more bang for your buck (so they say) IT does have more orifices compared to some other rocks, and that is benifitial when it comes to bio-filtration and such.