Grim, once it grows to adult size, it will need to be moved to a 20 gallon. My HUGE male leopard gecko is in a 20 gallon long tank and he would never do well in a ten. The better rule is: 20 gallons per gecko.
DKiM128, as you suggested, the crickets would be eaten by the cps if you put cps in the leos' cage. Also, the habitat of the leo and the habitat of the cp are two VERY different things. Leopard geckos come from the dry, rocky deserts of India, Pakistan, Afghanistan, Iran and Iraq, while cps come from tropical, wet, boggy, mineral-free environments of some parts of the united states. Putting the desert dweller leopard gecko with the tropical cp would be like putting a fish with a horse, which isn't the best transition.
Oh, and welcome to the forums!
Good luck!
FTG