Hornbooks are more detailed descriptions of law subjects that you will go over. These are particularly important if your professor has written the hornbook or articles. They go into depth about certain areas that you are expected to deduce on your own by the case method (learning by reading actual cases, rather than specifics in textbooks)

Start law school and see if you have trouble. If you do, it’s often advised to seek out a 2L or 3L who had your classes/professors and ask their advice. Oftentimes, law school libraries carry study aids so you can browse them first before buying them. These can definitely add up, dollar wise, so take a look at them in the bookstore and library before buying. They all have their advantages, but you cannot rely on them solely to do your work for you. The exams will test your abililty to issue spot, and these won’t help you to acquire that skill.