HI khakh9,
I think you should opt for masters rather than pg diploma because according to what i have seen here , it is better to have Masters for good job prospective and I think U of Waterloo and Saskatchewan are good to go and as I am a U of S student it doesn't mean i favoring It because a lot of MY friends here who are in masters are on scholarships which i think can reduce the financial stress overhead but ya try to choose 2 or 3 schools so that at least u can get into one of them and yes for U of S u need 70% overall in bachelors but rest depends on the supervisor whether he is willing to accept u as his student or not and I think u should get MEng instead of MSc as there is better scope for jobs for engineer students here in Canada.
if u have have the contact list of supervisors available on U of S website then it is good to go but if not let me know!
I hope it might help and do reply to inform me how u found this response...satisfactory or...!