CAT is merely a testing technique and frankly would be very difficult to duplicate without 1000s of questions in the data bank in which to choose.
As far as the changes to the test itself I would say most of us are under the impression that this is more or less tweaking and does not reflect a wholesale change to the material itself so please don't worry about those things unless people come out of the exam screaming everything has changed - it won't.
You should feel confident in passing when your test scores on material you haven't seen numerous times from eyeing the same questions over and over hovers at 80 percent or more. Being human means we tend to go back to the same questions with the idea that answering those same questions over and over means we are learning the material. Or we are learning the same answers to the same questions.
Be sure to change up your quizzes or take a good amount of time between reviewing the same material less fall into a false sense of security. No pun intended. 
Ask lots of questions and of course, GOOD LUCK with the exam.
