Well if you get a heat pad u need a thermostat. I know some people here are completely against using lights. I think lights are ok IF you can keep the temps up and provide them to thermoregulate. Grated belly heat IS better some heat is better then none.
The 40g i think is to big because people generally keep adults in smaller then that.
Also you need 2 TIGHT fitting hides
As far as feeding goes do you have a gram scale you can use?
Most people feed juvies under 500 grams like on a 4 day schedule. I feed every 5 days but as they get bigger you want to cut back to 7 days.
Also if u get a gram scale weight him and feed him 10-15% of his body weight if hes like under 1,000 grams
Btw dont take it as everything you do is wrong. I understand you have had him for 3 years and he is living and healthy but making sure his enclosure is perfect to what he needs is always better.