Dragonball comics can be downloaded at http://www.realitylapse.com/manga/dragonball.php.There are two types of downloads – chapters or volumes, volumes are combination of several chapters. Better download the volumes, since downloading each chapter will take longer time.
I’m using SideBooks app to view the comics on iPad. The files can be easily transferred to iPad via iTunes shared folder.
Or if you’re using Fedora, it’s automatically detected as mobile device & by using Nautilus it’s as easy as copying files into SideBooks folder inside the iPad.