There would be no need to re-register. You can login and submit that info to your current account anytime you like
you need to confirm your account info & TAX info asap. till the time you wont do that you will not get any payments from google Buddy
Well, you have to confirm your address.. but if you are opted for mail delivery, you don't have to confirm it. Filling ou TAX Information is not mandatory for non-us publishers.
payment method is check by default, you only need to confirm tax info if you are US publisher. foreign publishers don't need to confirm the tax info