Celcis,
You should mist your crested geckos atleast twice a day, this provides drinking water and correct humidity levels required for actions such as shedding. Don't worry if you never see them shed. You should only worry if they have dried skin on their "toe pads" or on their body in general. This means the humidity is/was too low or that the geckos are too stressed to bother with the shedding process. Sub-adults will shed on average once every 5 to 6 weeks or so. Most all geckos are capable of "changing" colors. They don't truly change colors, but the tints and shades they exhibit may change but, nothing chameleon-like. Just remember to keep a 70-80% humidity level and a temperature of around 79-83 degrees F and all angles of climbing surfaces.

Gekko Terra