Well, for my format, I used the CIA world factbook. For the information...much of it's made up, or an approximation based on budget calculators. For writing a Constitution, the best advice I can give is that you get your format first. People know basically what they want to say; the challenge is making it look nice. In other words, putting everything in its proper place.
I like to put the broadest categories first, and work my way to narrower categories.