A. It is okay to go to an university or an other school on a Dependent visa.

Acts of attending a school such as universities suite to the daily activities carried out with support from your family, so there is no problem.

However, in a special case of saying "I would like to receive a scholarship for foreign students" or "I would like to enroll in a foreign student facility", there are cases in which it is necessary to be a "student" visa, so it is necessary to contact the university to obtain the type of visa.

For both Dependent visa and STUDENT visa, 28 hours a week is a part-time job that can be done by Permission for Other Activity.

If you work any more, you need to switch to a working-visa.

By the way, when going to a university with a working-visa, there is no need to change if it is night class, but when you go there in the daytime it is necessary to change to student visa.