Hi again, Stan!

Feed your Dekay's snake 2 - 3 times a week, as much as it will eat in an overnight period.

For the light bulb, you will need to set up a basking spot. This is usually a branch to climb on, which has a section of the branch that is up high in the cage, and which is directly under the light. Next you'll need a good reptile thermometer. You'll want to set up the basking spot with the thermometer right there in the hottest place under the bulb.

You want a basking temperature of around 85 degrees I think (not sure for a Dekay's snake, as there are few care sheets for this species). If you measure the temp in that spot and the temp is too high, you can raise your lamp higher off the screen, or you can try a lower wattage bulb. You will have to experiment until you have the right bulb and height that result in the right temperature.

No one can answer your question exactly, because the temps in your room, the type of lamp, and other variables, make each situation a bit different... so trial and error are the best method.