Congratulations on starting your first BIG project. I myself cannot offer too much in the way of sage advice, but there's a book out there where several people do. It's called
Game Design Perspectives (http://www.charlesriver.com/titles/larameegames.html) that does a great job of describing the administrative side of game design. It goes over in detail the game design documents that will help you stay focused on the spirit of your large project from beginning to end. It also covers how to keep a team of programmers motivated, and focused on the task at hand. It also goes over some of the business aspects of game development like marketing and knowing your audience. It's not the most exciting read out there, but there's tons of good info in it.
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