1. Why would I switch to a shell that looks like the shell I already have? You should provide them with two themes by default and give them documentation on why you gave the XP Shell by default and then let them grow into something more...unique.

3. You need to explain this one better. You want users to be on their PC with access to their apps. If you don't boot their windows you will restrict them to only what you install on the jump drive. If you are going to go this route you should get BartPE and build something for them to use. Then again...this would make them think that it is like switching to Linux and scare away a lot of potential users.

4. Use BartPE and build a powerful and robust troubleshooting jump drive with a better interface than the Explorer interface.