First time repti owner - Sandfish

So I work at a pet store. It was inevitable. I brought one home. A sandfish. I was won over by his adorable face, his sweet disposition, and his willingness to socialize. What an amazing little skink! Now... I'm not usually the type to just jump into something. I did do my research. But I'm realizing there's not a great variety of choices on caresheets... Heating is my biggest worry. I'm not sure what he can endure. I don't want to fry the little guy. Or freeze him. From what I gather, the temp should be about 80-90 during the day, 70-80 at night. At the moment, it's day. So it's about 90-100 on the one side of the tank (I've read this is okay because they usually bask in much hotter temps. But as for how hot, I'm not sure), and about 80-90 on the other side. Basically, I'm looking for tips on the heating. I know the basics. But I never get into a pet half-way. If you could give me examples maybe of what you have used for these little pets, or what you think would be a good way to heat it, I'd be very much obliged!
Also, feedings. Insectivore, so it's crickets and worms. But I'm not sure how old it is (way to tell?) so I'm not sure if I should be feeding him every day or every few days... or how many insects. I have meal worms and crickets for him, but he seems to like the meal worms better because they're not as hard to catch. But I'm not sure if he should be getting those all that often because I hear they're a little more fattening... Not sure if that's true.
Any input you guys can give me is much appreciated!

Ideal daytime temperature should be between 80 and 85 degrees. Night-time temperature should remain between 70-80 degrees. A basking area should be created on one end of the enclosure to maintain a local temperature of 95-110 degrees to promote feeding. There are several methods for establishing the proper temperature range for your reptile. Using spotlights of variable wattage incandescent bulbs on the outside of the enclosure, under tank heaters or heat rocks or any combination of these.When using spotlights for 24 hour heat use red, night bulbs or a ceramic heating element to maintain day / night light cycle. Never place lights inside the enclosure where the reptile could come in contact with them and get burned. Use a thermometer to ensure proper temperature range is maintained.