You can use py3k with CPython, so there is no reason to make two jumps at once. It's like saying you might buy a Porche now that the roads are better. But you can enjoy nice roads without a Porche just as well!
Yes, but making a programming environment change involves a lot of disruption to your normal workflow. I agree that it's best to do it one step at a time in order to better isolate the problem when things go wrong, but I find it's also good to do multiple upgrades during the same period of time to maximize the value from the mental mode switch.