If you're writing a guide shouldn't it be stopping questions being asked? If a guide is created that creates questions wouldn't that be the opposite of a guide, some sort of ediug or something.
Just do it, just start it, people in here will probably go "I don't need it" that's because they're already using it. Any criticism; don't take harshly, any feedback; implement as needed. But if you post what you've posted and then wait for responses it's nothing but wasted time.
As far as your second question goes, if you have something, you can create a thread and link it and people will comment along the way, you can post updates in that thread and what not. But I don't think anyone will commit to a proof read of something that doesn't exist. Write the first chapter, start a thread, link it, get the feedback there, keep the thread alive, keep the project alive, etc etc.