Generally speaking, it is enough to master the score within one liter and one drop in solfeggio. Ear practice requires listening within seven chords and simply dictating the melody and rhythm. You can buy a reference book to learn music theory. The key to mastering more is to do more questions.
As for whether you want to take an examination of musical instruments, it depends on what major you take. If you want to take music education, you must take instrumental music and vocal music. If you take phonetic symbols, you only need vocal music.