Hi Marco Antonio,
for sure the PMPrepCast covers the topics from the PMBOK Guide, and also provides additional examples and explanations for some topics that are part of the exam outline while not being explicitly discussed in the PMBOK Guide. Yet for me it was important to study the PMBOK Guide as well, to keep it as a reference point for the main concepts and ideas. I find it useful to deal with some subjects from slightly different and complementary perspectives: I noticed that helped me gain a deeper understanding.
This is why an exam prepbook is also recommended; however, you don't have to, if you don't feel like. To be honest, I found it a bit hard to go through Rita's book; I read it because I had already bought it, but would not say it's a must. Nevertheless, in terms of perspectives I mentioned earlier, I found the Procurement Management chapter extremely useful, because of its detailed discussion on contract management.
Based on my experience, I would recommend to start practicing some tests (even 20-30 questions at a time) to test your knowledge and understanding so far, and then decide whether you may need a different perspective on some of the topics to improve your preparation, or if you just need some additional practice.
I didn't want to start practicing some tests until I felt I was "well prepared", so I postponed it for quite some time, but I regret that, because I learned a lot even with the tests and exam simulator. And they helped me adjust my studying and preparation.
Gabriella