Hey there vpv, the 5 faculties are pretty much the same but when it comes to practicing in US/Canada, the 1st fac. is best recommended as it's english program is CA approved (which entitles a student to work in all the 50 states and also there are very few english programs in Europe which are CA approved--4 I think).
Anyways if you plan to return back to Canada, then I would definitely recommend the 1st fac. 2nd fac. is more suitable for British students and 3rd. for Nrowegians. You usually have to sit an entrance exam (which is in basic chemistry, bio., and phys.) They don't really consider the grades that much (as the entrance exam is what gets you in). And trust me, the exam is not very hard. The only thing I can suggest is to take it as soon as you can, as you have a better chance of getting in.
We have a few canadians this yr. (there are about 5 in my class) but in general we do get a lot of students from North America (usually from the US). If you have any other questions just PM me and I'll get back to you.