I honestly feel it is better to study from the Compendium, but not take the test with it open. You aren't always going to have access to the Compendium. You may not score as high without it open, but at least you have a better understanding of your skills.
Every question that involves card rulings it gives the text of the cards. This is just like how you ask to see the cards when players have a question. The last time I had taken it, it was more up to date questions than it used to be, not that it affected me much considering that I've been judging over 5 years.
Be aware that the test is timed. You get 45 minutes I believe, but I never take that long. If you do not pass the exam, there is a brief period you have to wait before you can take the exam again. It will tell you which ones you got wrong, but will not tell you the correct answers unless you passed the exam with at least an 80%. The last time I took it I got a 95%. One of the two questions I missed involved tournament organizer responsibilities so I didn't care much since I'm not a Tournament Organizer.~KA