2) If you are a subscriber, then putting in the code will unlock all of the content from that book in all of the databases that are available through Insider. For example, without the code for the relevant book you would see only a one-line description of a feat during character creation. With the code you see the full rules. Similarly, without the code you would see only a one-line description of a monster on the game table but with the code you can see the full stat block, etc.
This is a very good sign to me. I was very concerned about this, as my gaming groups have always shared expansion books. With this system, we can continue to do so. We won't see the rules text in our electronic character sheets, but we never saw the rules text on our physical character sheets either, so I'm sure we'll survive.