If I am understanding the GoFlex Satellite correctly (and its not released for sale yet), it streams media to your iPad though its own wireless network. It is not designed to function as the typical external hard drive, and you can't upload files to the GoFlex Satellite from your iPad--you are always "feeding" it content from your computer, then viewing that content on your iPad.
I would like to also play movies, songs and books on the iPad which are stored on the drive.
That you can do with the Satellite.
I would like to transfer files and folders between the drive and the iPad 2.
This you can't do with the Satellite, AFAIK.
I am also interested in finding out how to move files from the iPad 2 to the GoFlex.
Nor can you do this with the Satellite, again, AFAIK.
For transferring files to and from the iPad, I believe you're left with the old standbys: sync via iTunes, or put on DropBox or MobileMe (depending on the particular iPad app; some sync to DropBox and MobileMe, some to one or the other).