You need a USB Falsh drive. i picked mine up (impact 128mb) at Wall-mart fot $28.
As for useing a MAC.............................just found the box in the trash!! you need OS X or OS 8.6 or above!!
NO you do not need to be ONLINE
hope this helps
lol, u can use a mac... you just need to find an image host & a usb thumb-drive.. like a SanDisk Cruzer Mini (or cruzer micro) that come with up to a gig of space; they are cross-platform compatible. i use PC at home & MAC at school.
the imagehost you can use is something like imageshack.us or something similar