Cool white and warm white refer to color range on a fluorescent tubes. When you mentioned them I was thinking you were talking of 4 tube fluorescent fixtures.

If you use metal halide or high pressure sodium you will probably only need one bulb over each growing area. One of these bulbs designed for plant growth is sufficient in the proper wave lengths to give good growth. The distance between the fixture and the tops of the plants, and size of the area illuminated will depend on the wattage of the bulb.

Yes they run hot and the light can scorch plants that are not used to it or are too close. So you need to be much more careful about using high intensity lighting. I can't give you a simple answer that such and such wattage bulb needs to be x feet above the tops of the plants. Perhaps Martin or someone else with more experience in practical use of such lighting systems could comment.