Depends entirely on your course. Some people might think ten hours of lectures was a tough week, others might have twenty as standard.
At the second half of last term I was doing twenty hours a week of lectures/labs and around five hours of private study every day. But I'm a third year physicist and all my options for this year occurred at the same time.
The major/minor thing only applies to first year, and some majors take up all three courses. Some majors take up two, leaving one subject as a minor and some courses take up one leaving two minors.