Is it recommended to configure something to automatically keep an RPi updated? And if so, which method (cron-apt or something else)?
There are pros and cons on both sides of this argument. On the one hand, by keeping your system up to date you insure that you have the latest bug and security fixes; on the other hand, by being on the bleeding edge you may become the victim of an unfound bug or security hole in one of the updated packages, which can prevent your system from working as intended. I choose to run the risk of an unfound bug, and have my Pi set up to automatically update using cron-apt. I also have etckeeper (note that these instructions are a little out of date and that installing etckeeper will default to using git and do an initial import for you) installed so that in the event I need to rollback and update I can do so without much difficulty.