No, a night drop is not recommended. You should have a constat hot spot of 90-95*F and an ambient temp of 80-85*F during the day and night.

The light that comes in from the window or simply turning on the normal room lights will be enough to provide a day and night cycle.

I would get a UTH and only use the CHE if your ambient temp won't stay above 75*. A UTH must be used with a thermostat. The cheapest model is the reptitemp 500r. It can be hard to find in stores but is easily found online.