It all depends on your career. If you're going to do a lot of writing or be an English Education teacher, then definitely so. If you plan to do manual labor all your life, then probably not. If you plan to work a store job and move up from there, then probably not either.
To an extent. Knowing your grammar and spelling is pretty important. But knowing literary elements and random facts on books and all that isn't necessary to know. We probably won't ever use it. I think a lot of the stuff they teach us isn't important to know for most people.