The binary format of the Project file remains undocumented for Project 2007. The best solution used to be to using the OLEDB provider, it would give you read-only access to the Project. But the OLEDB provider is not being included in Project 2007. Additionally, the database schema for Project is no longer going to published. Since the schema was published many years ago we’ve had a fixed base schema with only being able to make additions. When you publish a schema it becomes an API for access, and any API is an implied contract for developers. Keeping the fixed base helped us maintain our “contract” to keep backward compatibility. By not publishing the schema there will be flexibility for fixes and feature additions, especially around Project Server.
Your best bets, I’m assuming this is standalone Project, is either OLE automation through the client (which I believe is what you’re describing above), or using the XML schema.