You will definitely want to read these sections before starting on your own games.
By now you should be able to create a simple game. Read on in the tutorial to discover how to make it more interactive.
Now you're able to create a pretty sophisticated game, you probably don't need to read all of these sections - but Quest is a very powerful system, and if you want to master it, read on!
Most people probably won't need these features, unless you're creating something very special or very big!