Hardware issue on rooted Hero, suggestions?

I have found the "stock" RUU and am ready to flash it back to "stock" but wonder whether that's necessary. On the outside chance they tell me my button is not defective and send me home with it, I would hate to have erased everything I have done.

The faceplate around the trackball, which contains all four "buttons" is shaking and feels as though it might be ready to fall off.. well, not really like it's about to fall off, but with only 10 days left in my 30 day warranty, I'm nervous... The phone that's on display at the sprint store, which I assume has seen MUCH more use than mine, does not have this problem. Anyway:

1. Can I "backup" the phone in rooted state, restore to factory with RUU and "restore" back to rooted state? (too good to be true, right?).

2. If I just restore the nandroid backup I created during the rooting process, is that enough, or will a nosy tech (if it gets sent back) notice and cause me grief?

3. Will the inspection for a hardware issue even require a review of the software or even have to see the phone in use? If they agree the button is broken, will I be able to say OK, Ill bring it back tomorrow? Or, will that cause them to be suspicious?

4. What actually happens if they find out I've rooted the phone. I know the sprint police won't take me away. Will I actually void my warranty? Obviously, rooting the phone did not cause the button to come loose, right?

Thanks for your thoughts,
Pete