I'm not sure if I understand your setup exactly. I assume you mean you have lights over the cages acting as both a source of heat and light, and that these are shut off at night.
A basement room will likely need some additional heat depending on how warm it stays.
All of the species you listed can manage some temperature drop at night, and in fact probably require it.
As far as the room heater, do you mean it's a portable space heater with the appearance of an old radiator furnace? If so, it's like an oil-filled space heater. These are excellent and safe.
I'd set it for 80* or so and then continue to heat the individual enclosures during the day with their heat lamps.
Depending on the size of the room, you might consider using an external thermostat to control this heater. The "built in" thermostat you mentioned is likely only a rheostat and not very reliable. So even though the oil-filed space heaters are relatively safe (assuming that's what you actually have) from a fire standpoint, it does not mean they can't overheat the room and kill your snakes.
This has and does happen. The rheostat fails and the heater runs continuously. There are not combustive failures but the rooms can often reach dangerous temperatures within a few hours.
Also, an external thermostat will control the heater within a more acceptable temperature range - even if the unit is actually equipped with a thermostat and not a rheostat.
Make sure you select a thermostat rated to handle the wattage output of the heater.