Only use official materials. By the way, in the first pages of the official guide you find the answer to your questions about the first ten questions being crucial.
You have 4 books and 2 practice questions at the official material and 9 mocks paper based, 6 cats (you can 2 twice each without repeating questions), 3 quantitative CATs and materials for AWA and Integrated reasoning.
In my opinion, with 15 years of experience and more than 3K students approved since 2006, study other materials is a waste of time and money.
Remember that each official question was tested statistically to receive a score and be approved as an official question. It’s an unbeatable and impossible to reproduce method.
Study only official materials and create a pattern. When you finish, repeat the operation until you almost memorize each question.