UWO is a reputable school with policies that need to be upheld, but it is not strict by any means. Since the legal drinking age is 19, underage drinking is often given the blind eye. In residences, the policy is essentially, "If I don't see it, I don't know it's there," and dorm managers generally just care about student safety. The same goes with police—as long as everyone's safe, that's all that matters. Students drunkenly stumble from campus bars and dorm parties, and as long as they aren't disrupting anyone, they won't be bothered by the cops.
Attendance solely depends on your program and course. Some professors couldn't care less if you went to class or not, but those courses generally hold less learning benefits for the students. The professors who care about your attendance, contribution to discussion, and enthusiasm for the course actually enlighten your learning experience entirely. Even though it's a drag to have high school-type rules in a college course, you will gain the most from those courses, and undoubtedly do better on the final—if you attend class, that is!