For a 75 gallon tank you'll probably want a lot more liverock! Most recommend about 1-1.5 lbs per gallon of tank.
Better lighting will help the liverock grow corraline algae, the purplish stuff that you want growing instead of nuisance algaes, but it's not necessary. If you plan on having fish only you don't have to worry about lighting much except what looks good to you but if you want to eventually move on to photosynthetic creatures such as corals or anemones, and money's no object, get the lighting that those creatures will need to start with (depending on what you want at least power compacts, very high output, or metal halide)
You don't have to cure the liverock if you want to use it to cycle the tank. If you want to cure it though get a really big rubbermaid tub, fill it with the same saltwater you'd use in the tank, put in a powerhead, heater, and themometer. When you get the liverock scrub it really good paying special attention to any spots that look like something has died off, black spots, ucky mushy stuff, anything really smelly, etc then put it in your tub. Scrub it daily until there's no more die off, it should smell like clean saltwater. Then it's safe to add to a tank.