I can't speak for your lighting question, but one 250 watt heater is more than enough for a 65g. I ran only a single 250w heater for my 75g for over a year without issue. I've been running on one 250w heater on my 180 for over a week (while I wait on FedEx for my 2nd) and it has kept the temperature consistent. For a frame of reference, my house is usually 70 degrees Fahrenheit and I keep my tank at 80. Suffice to say, 250 watts on a 65g is more than likely overkill depending on how hard it has to work to raise the water temperature from its "natural" state in your house.