1. Yep, they eat mealworms and crickets. You can also give them waxworms as a treat once in a while. They also eat roaches (lobster roaches), and those are pretty easy to breed and keep.
2. 10 gal is fine for one gecko, 20 is fine for 2-3.
3. Girls get along with girls. Guys do not get along at all. Also, they need to be roughly the same size, or the big one bullies the little one. Generally you don't want to mix guys and girls until they're 60 grams or more (breeding size), and if you do mix guys and girls, you want atleast 2-3 girls and one guy (or the one girl gets mated repeated and gets stressed out). If you just want to breed occasionally you might want to borrow a male from someone, or keep him seperately, or you'll be up to your armpits in baby geckos.
4. They need some hides (one on cool end, one on warm end), a humid place (buttertub with a hole cut into the side filled with damp sphagnum moss), a shallow dish of water, a shallow dish of calcium/vitamin powder, and maybe a shallow dish of mealworms.
5. Generally avoid sand, bark, any particulate substrate that they can potentially swallow and get impacted. I like newspaper or paper towels since it makes clean up easy and it's very safe and cheap. The green reptile carpet is okay as long as the edges aren't frayed and pieces of it aren't falling off. Tiles are an excellent choice since they hold heat and are easy to clean. Sand is okay for older geckos, but again, impaction is always possible.
6. There have been reports of geckos living up to 30 years! But seeing them live for 20 years is pretty common.
7. Not too sure here, might want to ask some of the breeders here.
8. Yes, there's a couple different variants. There are pattern variants: normal, jungle, abberant, striped, patternless; and color variants: tremper albino, rainwater albino, les albino, snow, blizzard, melanistic, hypo, and tang, to name a few. And yes, they can all breed with each other and create babies.
-Lemur 6