You're going to want the reptical and the nekotn-rep. You might want to make sure that your vitamin supplement does not have d3 as well though, since too much d3 is can be harmful.

I would go for the 20 gal (I assume it's a 20 gal long) so they have more room. I don't know if that's enough room for that many leo's though.

I can't help you on the rest of that, somebody who has more exp with leo's can probably answer those for you.