I say this since the pet trade floods the market with poor specimens that often end up in the hands of inexperienced, or more likely ill-informed keepers.
What can we expect if we do things right with a collared in captivity. I'd venture to say 10+ years.
Coloration is of course extremely variable with lizards. For example, in many C. collaris populations the males will only get as colorful as an airbrushed piece of dirt (some may think they are beatiful though). There are a few populations around that produce awesome lizards. A few regulars on this forum breed these lizards quite regularly...Will Wells and PHEve probably have them available right now. You can never guarantee the color of an adult lizard by the baby, but you can significantly increase your chances of getting an outstanding speciment by purchasing from these breeders. Expect to pay $15-$25 for shipping, but this is worth the cost as the quality is met. Also, support those who are experienced keepers...not some kid working for $6.00/hour in a petstore. Breeders are very forthcoming with information and helpful advice.
Back to your question. When I was breeding more regulary (the lizards actually) I would often see hints of blue coloration in the tails and hindquarters around 1.5 months of age. By 6-8 months you can expect to see big changes...it could always take a bit longer. Things that can affect color are stress levels, mating behaviors, natural vs artificial lighting etc.
Tameable...Oh yes very much so. Start with a young lizard and you will likely get a lizard that likes you more than its cagemates :O) I've only had a couple adults that were collected in the wild that seemed had no hope. Even they will settle down in the right hands 
Hope that answered your questions.
John Eddington
