Most franchises have a manual that is distributed by the parent company. Reading this book from cover to cover can be more eye-opening than any other research. By looking at what the company has codified and put down on paper, corporate organization, goals, expectations, and policies toward employees can be ascertained.
Manuals are sometimes available for loan upon request from the parent company. Barring this, it may be easiest to borrow a manual from a current franchise owner.