i would reccomend an ebb and flow tray in rockwool cubes if you plan on going SOG, i mean why bother to set up a root system if your constantly going to be harvesting and replanting clones, just throw away the rockwool and start over plus it works great for your fresh cut clones, also you shouldnt really worry about how many plants cause with sog your just smashing as many together as possible

also for the light you should have 50 watts per square ft and i beleive thats at optimum, a hydro store will tell you like 20-30 watts, i use a 400 watt switchable ballast for a 6sqft room and can get a lb out of 4 plants