I need to have different footers for left and right pages in Apple Pages to make a sort of book layout in which the page number is close to the outer page. How is this achieved?
Facing pages/mirrored pages is not possible in Apple Pages v5.x. The last version of Pages that supported facing/mirrored pages is v4.x (iWork '09). If you have access to a copy of Pages v4.x, v5 can save in that format so you can use the file in '09. Otherwise you would need to use an alternative product, such as Microsoft Office, that supports facing pages.