How far away from my plants do the lights go?
The lights in your grow room should be as close as possible to the plants without burning them. There is no such thing as too much, unless there is sufficient heat to dry out and burn the leaves. A good rule is to put your hand under the light, if its too hot for your hand, chances are that the plants will be too, so move the light up until your hand feels more comfortable. For seedlings and clones, I keep them a little further away from the light, because they are very susceptible to burning and drying out, at these stages.
Efficiency is very important when choosing a type of light. The wattage is not the most important thing, as you can see below, different types of light produce different amounts of lumens per watt. A 300 watt incandescent will produce about 5100 lumens. While a 300 watt Metal Halide (just an example, they do not come in 300 watts), will produce 27,000 lumens. Obviously far more efficient for growing, while still using the same amount of electricity.
