You wont be able to find out the class average, I have had some classes where they give the averages and breakdown for midterms but never the final grade or anything. Maybe if you ask the prof but I doubt it, most of them see no value in giving out the averages. In the end it doesn't matter if you were above average because grad school, med school, etc only look at your final marks not where you were relative to the class. From what I have heard a lot of classes aim to have the average around 70%. This isn't necessarily true but thats what people always say.
Using letter grades, 12 or 4 point GPAs are standard in university. I dont know why they switched to this system but its the standard. For the
GPA conversion table
For Life Science, the minimum grade to get into the honours programs is a 6.0 CA. It can be higher for limited enrollment programs where you are competing for spots.