As I have said:
Even before this book idea came to light I had started jotting down ideas for 2 books for ocPortal. One aimed at the Administration of the site and One aimed at Development of the site.
Development concepts should be avoided (or very minimal) in this book because a WHOLE book could (and should) be written on that subject.
This book should be aimed at Basic Administration but although I use the word basic that does not mean the topics and content can't be advanced. In fact they should be. We just shouldn't be discussing much about Development as that is a small segment of the community and many Administrators don't want to learn that. They do want to know how to layout and manage their site and install things developed by others. They want to know how to make their site pretty and several other topics that fall under the administrators role.
That said Intermediate to Advanced topics should be the main focus but in a clear easy to understand format. Writing PHP code should not be a topic or at least a very minor one.