To have them all on your iPad at the same time you would need enough free space, which you won't have on a 16 gig model.
You might be able to download them on your computer's iTunes, possibly via the Store > Check For Available Downloads menu option, or by going to the Purchased link under Quick Links on the right-hand side of the iTunes store homepage. If you can you can then sync/watch them one at a time to your iPad, or stream them from your computer's iTunes to your iPad via homesharing : homesharing will need to be enabled on both your computer's iTunes (File > Home Sharing menu option) and iPad (Settings > Videos) ; both will need to connected to the same wifi network ; and iTunes on your computer will need to be open ; you should then get a 'shared' library option in the Videos app on your iPad