3.0 cleanup

Cleanup the early chapters a bit. I'm starting to quickly read the entire book and look for obviously wrong or content that confuses me.
Yeap, mostly redundant or half hearted.
Or even worse a half true description in the book and an outdated info in the API docs.

Let's focus on keeping the API docs
1. up to date
2. detailed enough
3. well linked FROM the book
4. well linked INTO the relevant book section