Awwwwwwwww - he's adorable. Will he get much bigger?
Yeah, I think it's still a juvenile. I'm not sure what gender it is, but it's probably a female as most pet stores sell them. They usually get between 6 and 10 inches long. I'd say it's just over 5 inches now, including its tail. It just shed last weekend.
The only downsides are having to feed it worms, and it can't drink regular tap water without something in it to kill the chlorine, and having to keep the light and heater on its cage on all day, but you get used to it.
I have a wire mesh on top, and leopard geckos can't climb walls, so you don't have to worry about them getting out unless you have fake trees it can climb or something.
No I don't know a thing about how to take care of one. 
