Feeling inadequate :/

[UncleChester]

Your tank size is definitely small for the long term, but they should be fine until you can save up for a larger vivarium that will last their lifetime. When you do upgrade, you can keep your 12x12x18 as a spare tank for quarantine purposes, so nothing is wasted.

However, I see the vivariums, and the terrariums with the layered bottom, and I just don't know how to do this stuff yet. Plus, how in the world do you clean it?!

Some will have drain holes, others will have a way to send a flexible tube in through the top to siphon out water like you would a fish tank. They're called "False Bottoms" if you want to google the term you'll find hundreds of references.