Wow, you leave town for a week and there are a ton of new names, let me help:
Leos in the wild are not completely nocturnal, they do come out at dusk and dawn for a time. This is also observed in captivity. I am a huge fan of lights with UVB as, in my own experiences, my leos grow faster and eat more after only 3 days with a UVB light. Your mileage may vary, but I'm the board's UV advocate and, at the very least, I would suggest a light (even a 40W should be enough) for daytime light and heat, this offers the gecko a better simulation of time. UTH is great for belly heat at night as others have said, any of the major brands are good, we mainly have Zoo Meds.
I used to use some random vitamin mineral supplement, but having read up before getting into crested geckos and finding out their crickets are best dusted with TRex's Leopard Gecko Dust, we've been using that for everything. It is a complete formula of calcium, trace minerals, and vitamins. It is your best option for dusting, a pure Ca dish is recommended to be placed in the enclosure, especially for females.
Substrate the best, especially for young is papertowels all the way. Tile is not a bad option, but harder to get UTH heat through.
BTW, I always say, pick up the book: Leopard Gecko Manual, it is usually $5 or less and a lot of "old timers" still refer to it.
Good Luck.
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0.1 Albino Leo Gecko
0.1 Crested Gecko
1.0 Dear Boyfriend
Departed: Harvey and Spock