The short answer is, not very, certainly in the case of the English universities, which can trace their histories back to the 11th-13th centuries. In their early days, Oxford and Cambridge existed solely to train men for the professions - the clergy, predominantly, but also law and, rather later, medicine.

Significant aspects of the curriculum were compulsory - perhaps most peculiarly, to our eyes, the modern University of Cambridge required all undergraduates to take two years of mathematics before embarking on other courses of study until well into the 19th century.

Teaching in the medieval universities was in the form of compulsory lectures and examinations were oral.

For more on all these aspects, while you wait for for a hopefully fuller response to other aspects of your question, you could look at the relevant section of the FAQ and at these earlier answers of mine concerning the Oxbridge exam system in the medieval and early modern periods.