^
I'm not familiar with Canada's college system but I'm sure all you need is a pass (50) to progress to do the next year.
It's different from highschool because in those times you usually need to get more than a pass.
I haven't heard of people getting booted out of the uni too often. The only reason that I can think of as to why would be that they have cheated in an exam (in some cases, in their final year and they wasted all their time studying from the start - have to apply to another uni but not necessarily get in with a bad mark against their name), or they plagiarized in an assignment. There are different levels of plagiarism which I was told about in first year but forgot now.
The 'how hard it is' part depends on your course right? Normally the harder courses like Med/Dent/Pharmacy have higher expectations because everyone else is competing with each other kind of and they are all really smart students.
Thing is, the motivation to study and do the required work is the hardest thing. Haha. (Infinite distractions.) :/
You should be ok, most people get in and out (of uni) fine.