Snoopy is right, commonly you would be using a turbo manifold rather than a header. I wrote that in there partly because there are always those out there that have a custom setup (or simply want a custom look) and so opt for a header instead of the manifold, and partly because a lot of people believe that a tuned header provides the turbo better power (the truth to that is questionable). I once saw a beautifully done turbo header... all stainless steel and powdercoated, but it had darn near 2.5" pipes... Rediculously oversized because the guy was told that the turbo HAD to have HUGE tubes in order to work. After many troubles the guy changed to a manifold and found a lot better response time and power. It just didnt look as good.
The refrences about tube lengths is for N/A engines. Turbos generally need to be as close to the exit ports as can be (or you get a lot of lag). Now, I have heard a few experts claim that they can mount the turbo further than normal from the engine and still maintain low lag, but since I haven't seen it and dont know how to accomplish this, I cannot elaborate.
I also want to add on to what Snoopy said... The exit pipe will have something to do with spooling time as well. If there is backpressure there, then the turbo is having to force the exhaust out... thus losing efficiency and creating some lag. In other words, on the exit side of the turbo, bigger is definitely better.