Success! The PRS-350 arrived, and my 700ish page PDF file of recipes looks great on there.
I used OpenOffice Writer to format the recipes with a page size that fits the reader. Once it was finished, I exported the document to PDF.
For navigation, I created one main Table of Contents at the beginning (Soups, Entrees, Desserts, etc). Then, within each "chapter" or section, I created a more detailed TOC (list of soups in the soups section, etc).
to everyone who offered advice and encouragement!