The Tales of Zestiria site updated with all the recent reveals.
First off, you may notice the main page has the illustration for the boxart in pretty decent quality (the product page has it up as it'll look in the packaging).
So 7-Eleven's Japanese website has a page up detailing its preorder bonuses for Tales of Zestiria. Alongside the normal preorder bonuses (exclusive Mystic Artes from past games+rubber strap), you'll also get a costume for Sorey with 7-Eleven themed colors as well as a 7-Eleven themed healing arte.
(I'll post what the preorder Mystic Artes are as soon as Baba reveals the last one)