Studying the text carefully and understanding all the grammar rules and usage conventions is not enough to prepare you for class, let alone the exam. You will be tested, not on how well you understand the grammar of the language, but on how well you can speak and comprehend the language. "Knowing" the language and "using" it are quite different. The latter involves skill acquisition which comes with practice. In order for you to participate in class you will need to be able to apply the material in communicative activities.
While it is natural to rely heavily on the textbook during the initial stages of studying new material, you will want to rid yourself of the visual "crutch" (i.e the dialogues and exercises printed in the text) as soon as possible. Your textbook's primary value is in preparing you for the oral/aural practice. The text provides the starting point for practice, but the final test of your control of the material is the ability to comprehend, and appropriately respond to, the material without relying on the visual cues in the text.