Hi nounstoverbs,
You ask a number of good questions. To start, there are a variety of different study materials that you might use as you prepare for the GMAT - so you should consider how YOU best learn (along with the specific areas that you'll need to work on to hit your Score Goal). Since the Official GMAT is a remarkably consistent and predictable Exam, the content of the GMAC Official Guides does not actually change that much from year to year, meaning that you would be fine using the GMAT2019 during your studies.
Since it sounds like you're just beginning your studies, then it would be a good idea to take a FULL-LENGTH practice CAT Test; you can take 2 for free at
www.mba.com (and they come with some additional practice materials). If you want to do a little studying first, so that you can familiarize yourself with the basic content and question types, then that's okay - but you shouldn't wait too long to take that initial CAT. That score will give us a good sense of your natural strengths and weaknesses and will help provide a basis for comparison as you continue to study. A FULL CAT takes about 3.5 hours to complete, so make sure that you've set aside enough time to take it in one sitting. Once you have those scores, you should report back here and we can come up with a study plan.
I'd like to know a bit more about your timeline and goals:
1) When are you planning to take the GMAT?
2) When are you planning to apply to Business School?
3) What Schools are you planning to apply to?
GMAT assassins aren't born, they're made,
Rich