Yea, just feed as much as they will eat, leos need to be fat!
(not being sarcastic atall).A habistat mat thermostat will control the temp of your heat mat.The heat mat should be covering 1/3-1/2 of the enclosure.Leaving a hot and cold end for the leopard gecko to thermoregulate (keep it's body temp at what it should be) as they are cold blooded, as all reptiles are.
When young the diet should consist of;
Small brown crickets (slightly smaller than the leos width of it's head),
small mealworms (no morio or adult ones),
butterworms,
waxworms.Thats about it, but butterworms and waxworms are only for occasional feeding.You could also try small locusts, but they have serated spines on there back legs and they are not really neccesary when you have all the other foods commonly available which are cheaper.
When adult, or nearly adult they can be fed;
Adult brown and black crickets
small-medium locusts,
morio mealworms,
butterworms,
waxworms.And others
large mealworms,
Unless it's a giant form of leo (which you can get) 10inches from the highest object in the tank to the top of the enclosure and it will not be able to get out, mine have tried and failed (Both my tanks which I keep my leos in are open top)
Mine are glass but the leo may be able to climb out on other cage materials.Leopard geckos do not need light and tbh it's pointless.They are nocturnal so you will rarely see them in the day, and if the lights on it may scare them when they would usually come out anyway.Mine sometimes sleep outside their enclosures!