The watt rating on a bulb is the power it consumes. In common florescent hoods, you will get a set wattage for each length of bulb, 48" bulb is 40 watts, 36" bulb is 30 watts, etc. Incandescent bulbs release most of that power as heat, good for reptiles, bad for fish tanks. Flourescent bulbs are cooler running, and the exact light they give off depends on the stuff used to flouresce, different chemicals give different light bursts.
So, in your hood, you may be limited by the length of the tank to certain types of lights. In order to get more wattage in a hood, you can get a compact florescent, which is a long bent tube or two tubes melded together. This can give you a 21" long 55 watt bulb for example. It takes a different plug and ballast to power it though so it all adds up in cost. So, in order to get the light you need, you first start with the tank size and how much light you need, then you narrow it down to the budget you have to work with.
Color temp is how the total light produced by the bulb compares to a star, with the lower numbers being yellower and the higher numbers being whiter or even bluer. But that does not describe the individual peaks at different wavelengths that were averaged out to that color temp.
You can look at a spectrum chart with many bulbs, and see the individual peaks and how broad those spikes are in each color wavelength, but it is still very confusing. My favorite bulbs look totally different on the charts, one is a nearly flattened bell-shaped curve, with narrow spikes in blue and green. The other looks like a heart rhythm, with high peaks in both blue and green and the highest peak in red, but when it is on it looks whiter than the other.
After saying all that, the best thing to do is to simply ask us, or other forums where people have used the various bulbs and have developed opinions, the bulbs are too expensive to just buy and try them. Bulbs will work differently in different setups due to the different ballasts used.
Now, you don't want the 12,000K bulb, that is typically for salt water and has too much blue which is what coral needs. The 6000K is probably fine, but there may be other choices there that will also work well. I have a 9325K GE Fresh and Saltwater bulb that is great, if you can find that you might want to try it.
But, let's be certain you are not mixing up florescent (two pin) and incandescent bulbs (screw-in), the hood you have will accept one or the other. Other types of hoods may take 4 pin compact fourescents.
