We are no longer keeping the list of preorder distributors as the list was not complete and the headset seems to be out of stock on most places anyway. You can click the “Visit official website” button on the steam page to get to an official distributor for your country. Or just try googling.
HP provides one year worldwide warranty, meaning no matter what country you buy the unit in, you can claim warranties in your country as long as there is an official HP distributor for the product in your country. This warranty also covers dead pixels. You can read more info about the global warranty on the HP website.