Well, what kind of soil mix are you using, and is there perlite in the soile? This will determen how much water you need to use. A rule of thumb is to stick your finger into the soil and if the top 2 inches are dried out you should water.
With the light, depending on the temps, you want to try to get with in a ft of the top of plants. If you place the back of your hand at the top of the canapy and hold it there for a few minutes and it is to hot to hold it there, then it is too hot for your plants.
Adieu