All apps, music, movies, books, etc. will be available to you. Basically, anything purchased on that iTunes account will be available to everyone in the family sharing group.
Once family sharing is activated, all purchases made from that point forward will be available to everyone in the share group, but to find the purchased content, you have to go to "Purchases" and then select the member of the group, then browse their purchased content. From there, you'll be able to download anything someone else purchased in the group for free.
The downside to family sharing, is you will not be able to "stream" music like you can now. For instance, once family sharing is turned on and your wife purchases a song...it will not automatically show up in your Music app for streaming. In order for you to play that song, you'll need to go to Purchases, then select your wife's name (it will show up automatically if your using family sharing), and then download the song to your iDevice. With Apple Music coming online, this will minimize the pain (assuming you subscribe to the $14.99 plan), because you'll be able to stream the entire iTunes catalog without worrying about what was purchased or not.
All apps, books, movies, etc. will behave the same way as music. You'll need to browse the other person's purchases in order to download it to your device.
Hope this helps.