Use the actual wattage rating, not the "rated" part...here the 100w equivalent draws 23w actual, so yea, use 4. There is something similar to what your describing called plug moldling...flush mounts to a surface, but has regular old 3 pronged outlets on it...I've not seen what your describing exactly...Are you in the USA? If so, go get 1 single bulb fixture, mount it to the top, 3 "y" socket adapters (turns 1 socket into two), screw this into the single bulb socket you mounted and then screw the other two "y" adapters in to the first adapter and then screw in your 4 bulbs. If your not in the USA you may not be able to find the "y" socket adapters. No, it's not a good idea to start seedlings on 12/12...let them veg long enough to get a root system going, (a couple or 3 weeks) then flip 'em to 12/12...if they don't have any roots, you won't get any buds. They aren't going to grow above ground that much the first 3 weeks anyway...they are focused mainly on growing roots at that point.