For a 2 by 3 foot space, two "100 watt equivalent" (5000K) LED bulbs, constantly left on, are sufficient for lighting.
It is also possible to buy a temperature controlled thermostat outlet, and plug in a tiny 250 Watt space heater to that to supply warmth. But for citrus growing inside a heated house (and in the geographic location you are) that will probably not be really necessary. Even without an added heater the temperature is still likely to stay about 63 F (17.5 C) in there, with the lights being on, even though it may be 0 C outside.
Plan to water about once a week, maybe twice a week if the containers are not really big enough.