Welcome to HC! Huey is beautiful. What is the name of the UV light you purchased?
Turning the heat off at night isn't an issue if the temps are not getting too low. If you are using an air conditioner, or are planning to, you may want a night heat source to get a good gradient.
To my knowledge, chams are diurnal so feeding an hour or 2 after the lights have been turned on and the cham has had time to warm up would be sufficient. Someone with more experience with chams however will be able to provide more info.
Reptiles manufacture their own d3. I wont get into the process, but that UV light you have is how they do it. So long as they have access to unfiltered UVB, they will produce d3. (Which allows them to metabolise calcium.)
If you are using a quality light, you don't need to provide d3 as a supplement. truthfully, I don't know if chams are even capable of digesting d3 or if they are one of the reptiles that can. (Most basking species MUST get their UVB from a light source as their bodies can not extract it from their food.)
Chams are a low level UV reptile. They don't require a super high dose of UV to stay healthy. Are you providing plenty of foliage for the cham to retreat under or in if it opts to get out of the UV? If you aren't, you should be.
I hope you enjoy the site.
