If there are Vietnamese students coming to study in Taiwan, must they learn Chinese?

Not necessarily. If the student is coming to Taiwan to study in English, he must pass the English threshold. If you are taking a course in Chinese, you must pass the Chinese Language Proficiency Test at level 2 or above.

What is the main job of the Hanoi Education Center in Hanoi, Vietnam?

The center is subsidized by the Ministry of Education. The school is established with the Social Science and Humanities University Cooperative of the National University of Hanoi, Vietnam. The main work is threefold: one, promote Chinese, second, promote study in Taiwan, and third, promote academic and cultural exchanges between the two countries.