There is no US list - the N9 wasn't officially released here.

You can flash firmware from other areas - thus removing the branding on the lock screen and perhaps a couple of other carrier specific applications.

You need to more than likely flash the EMMC alongside the standard firmware. I would say that it would be to your advantage to search for "flashing firmware" and look for other success stories.

I had flashed my Australian sourced 16gb N9 with the Northern European firmware - this is basically the "standard" firmware - and didn't have any issues. I flashed back to Australian firmware, did the OTA PR1.2 update, still no problems.

Well... heck. I didn't see the other posts before I responded. Good advice above!