You'll be paying in CAD... yes it will be higher... the better Canadian schools are as expensive or more expensive than their British/Australian counterparts (of similar calibre), except for certain subjects (like Arts). What I mean is Commerce, Science etc cost a lot more... not sure about Social Sciences.

I know tuition is higher depending on what subject you're studying. If it's only Arts, it could be cheaper - Commerce, other Social Sciences, Science and Engineering should cost more than Australia. In Australia Commerce and Engineering cost the same while Arts are slightly cheaper.

A look on the university website should give you a quick answer. If you want to go to McGill, their website should have an estimate for the amount you need for living expenses.