I agree with the air flow. The hood is open fully in the back. So dust will get in regardless, but I know heat rises and I I am going to make sure that the heat has a place to go on top.
The light itself is going to be about 2 to 3in above the waterline. It also has a plastic protection cover that covers the lights and protects them from water splash. Here is another photo with just the white lights on. I might keep both blue bulbs. I guess the blue brings out nice color. I was told that I couldn't do corals with this light, but I have seen tanks with just this light with corals and growing well. Not the corals that need a lot of light but just some basic easy to grow corals. It looks bright enough. I am not going to put corals in my tank, but I am just saying the light is brighter than I thought. LoL