I'm going to write a pretty short reply here. The architecture I set out is designed for ease of addition and edition later. Simple as that. It doesn't need to be huge, like I gave in the example. However, we could just keep adding chapters per type of roleplay. The idea of Units is just to organize the types of different roleplay, really. Although it's not needed, it would assist later in searching and give a nice mechanic. It wouldn't hurt it to have them, especially if the first few chapters are the Quick Start Guide and roleplay theory models, anyway.

What you described is just making an index for several guides. What is far more beneficial and integrated is, in fact, having the core system applied to branch topics. That way, every type of roleplay is connected on a conceptual basis. With a good editor working hand in hand with an expert writer, it won't be that hard to get it right. My suggestion her e is that if it does in fact become a problem later, we rework it, but I would staunchly advise trying to keep it for now. 

As for the latter half of your idea in turns of scrapping for player and GM guides, I'd say to address that at a later date, too.

You're entirely right in the sense we need to get objective goals set, but we needed to make headway in getting everyone aboard.