Fluorescent Lights

FAQ: 

Which bulbs are tuned on/off from the two on/off switches on the six tube T5 flixtures?

One switch operates the two center lamps (3,4) and the other switch operates the four outside lamps (1,2,5,6).

Is it a problem if water or water vapor gets on the top side of the T5 fixture?

There should not be a problem. The ballasts are sealed and the lamps are protected from condensation from above.