I wouldn't use a day lamp for leos they are pretty sensitive to bright lights. I use undertank heaters for both of mine with no lamps.

The moss is terrarium moss or sphagnum (sp?) moss. I like papertowels though cause they don't get stinky like the moss does. I just mist the humid hides every other day.

The pure calcium should be in like a milk jug cap and keep it in the tank 24/7. They need to have it. I have seen mine eat it multiple times.

Also, remember that two females can fight. Mine did and I had to seperate them. One female wouldn't let the other hide, eat or drink. She was also biting her. So i had to buy another set up. No one told me this could happen when I first got my leos.

A 20 gallon is kind of hard to fit all those extra hides in. So I would start with one leo in one tank. They do a lot better by themselves.