GMAT is nothing compared with GRE, not so difficult but you should get yourself familiar with the types of questions. I took it long time ago, and got 690 just by going over the official (by ETS?) preparation book. It was for fun, since at that time I just finished my GRE and still hot. Somebody told me if you got 750 or higher, business schools like Harvard or UPenn will invite you to apply. Don't know if that's still true.
not really.
GMAT is designed to test u knowledge wide, such as basic economics stuff, accounting and analysis ability. GMAT vocabulary is fairly similar to TOEFL vocabulary.
If u study in North American business school, it won't take 2 years to memorize thoese words.