For some marketing ideas, check out the Software Packaging Association's Marketing Tip of the Month. You may also want to read Interactive Publishing Alert, Rosalind Resnick's excellent e-newsletter about marketing, advertising, and interactive publishing. For a wealth of development resources, check out Teknobrew. Allen Communications provides a couple of white papers which delve into design and authoring issues. One of the largest portions of your development process is developing or procuring the content you need for the project.
Content can be a touchy subject.
If you have created your own content, you'll want to peruse Copyright Basics to learn your rights, and how best to protect your work. If you plan to use content from other sources, you should study Intellectual Property Law For Multimedia Developers. The Multimedia Law Handbook also offers practical advice in both obtaining and transferring rights to multimedia developers and distributors. You'll no doubt want to visit the US Copyright Office at some point in your research. Start by checking out Cybernetix, Jeffrey Petkevicius' home page.