lighting - fluorecsent and mh

I was thinking about building a nice sized box. I'm just starting off. I was thinking about using 40-42watt fluorescents on the sides of a couple plants and a metal halide over the top... Does that sound like a good idea?

How far should I keep the metal halide from the plant? Is 1 metal halide going to affect my electric bill a lot?

Is the more light you use the better?

how many watts is the mH?

place your hand above the top of the plant so the back of your hand is facing the light. Move the light down until your hand becomes just a little uncomfortably hot. Then that is the distance you want to keep it. It will be fine with the CFL's on the side, and the MH on top.