You don't have to before you go to school, but piano for music teachers is compulsory. You will have piano lessons for one to two years, and then there will be a final exam. If you are not a piano major, you don't have to learn piano after the final exam, but as a music major for teachers, I suggest you learn piano well.

It doesn't depend on the instruments you learn. If your major in the normal school is education, it should be called musicology, and there are also music performance and dance majors. Except for music performance, the other two majors are normal. You are admitted to the university with pipa, and piano lessons are compulsory only when you go to the university, understand?