Worked on the initial design. I need to work through an actual project so that I can better grasp what is needed. So I created an account with https://jamsolutions.aceproject.com to try out their solution and figure out what else I need.
http://www.aceproject.com is a good product to base my design against. On a side note, this project is for managing all project types, not just film. Work has begun, but it's only the data stuctures side of things.
http://www.project-open.org/ is a good reference for billing information.
http://www.phprojekt.com/demo has a good layout.