Thanks much, Scott. Very helpful info. I'm going to try to do both -- jailbreak and unlock -- once I replace my phone. The old one is not going to be of any use anyway, so I can mess with it and not worry about bricking it or otherwise messing it up. Then if that works out, I will jailbreak my iPad. As I understand it, iPad comes unlocked.
When people talk about "root," are they talking about getting full access to the OS source code?