Do I have to speak Dutch?
No. Of course, international students are in a different position from Dutch students. If you do not speak Dutch, certain jobs will be impossible for you. Even if you speak some Dutch, the job may require the fluency of a native speaker. However, even without Dutch there are a huge amount of opportunities for international students.
Nevertheless, learning some basics can help impress employers and integrate more fully into the community. In your first year of study (bachelor or master) you are eligible to take part in a free Dutch Course offered by the university. If you are a third year bachelors or a masters student you are also offered a free German course. Certain conditions apply.