Hi, Welcome to the Gecko World.lol And the Forum. I will try and answer all your questions.
You Should use a digital thermometer with a probe, as you need to measure the substrate temp. That should be between 88 and 93. the cool side can be high 70's to low 80's. The stick on thermometers aren't accurate. Also you will need some way to regulate that under tank heater as they can't regulate their heat output and they get very hot. I use a rheostat which is like a dimmer switch and you adjust the undertank heater manually. Or you can use a thermostat, you set that to a temp you want and then it takes little help on your part except to check it to make sure its working righ tand to adjust to make sure you have the proper temp.
You will only need more heat if it gets too cold then use a reptile infrared light as they can be sensitive to bright lights being nocturnal, they dont' need a basking spot. They also don't need uv lighting as long as you supplement them properly.
You dont' have to feed mealworms, but do offer variety. The crickets are fine and I feed mine as much as they want in about 20 to 30 minutes. Then take out the rest of the crickets, they will annoy your leo and chew on him if they have nothing else to eat. you will also need to gutload your feeders, I get my gutload from
www.cricketfood.com. You can also feed silkworms, superworms, lobster roaches waxworms or butterworms. Go easy on the waxworms, they are high in fat.
I just wanted to make sure that you have the correct supplements, you should have a dish of pure calcium in the cage at all times, I use milk jug caps. Also dust the crickets with pure calcium 5 days a week, a multivitamin one day a week and vitamin d3 one day a week. They can over dose on d3 thats why you only use it one day a week. This is if you have a baby/juvenile.
Also what kind of substrate are you using, I want to make sure the petstore didn't tell you to use sand or any other loose substrate. They can cause impaction and kill your leo. Leos lick their surroundings and ingest sand or other loose substrate then is causes a blockage and they can't pass it. Things that are safe to use are, papertowel, slate/tile, non adhesive shelf liner, or reptile carpet.
I hope this helps you some and that you enjoy your new leo.
Kristy