Dont you have any other operating system except win 64 bit ? You need to use rootfs and emmc to flash completely (recomended). If you just want to flash but need keep your existing files in the internal 32 gb then you just flash the rootfs only if you use the 5gb emmc image you mentioned avove then it will provide you with 5gb optfs i.e 5 gb for installing games and apps and the second file you mentioned will give you 2gb optfs space. So you can use anyone of them : the last file you mentioned is the rootfs i cannot help more as i dont have flashing experience in 64 bit systems