Returning to stock ROM - A couple questions

[SweetBearCub]

To cure the various bugs on my phone (custom ROMs are fun, but they never work completely right for me..), I'm planning to go back to the stock Sprint ROM (downloaded from the sticky in the upgrades section), but before I do it, I have a few questions.

1) Do I need to relock my phone before I do this? Its not being returned to Sprint for a defect. I doubt it, but I need to know for sure.

2) What registry changes do I need to make to enable stealth tethering? (I prefer the actual registry entries, not a CAB file).

Thanks!