I don't know why you would want to know this because it shouldn't affect any decisions you make at all, but i'll give you the facts as far as I can tell.
I do a couple of commerce subjects, and without being at all racist, the majority of people who study commerce are international students. Of those, most of from east asian countries (Japan, China, Hong Kong, Malaysia, etc) and a minority from west asian countries such as india and pakistan.
I would say in terms of the percentages that international students make up around 70% of the commerce student cohort.
Tends to mean you have a lot of different nationalities in one tutorial, which is great because everyone has a really different perspective on the things you study etc.
As for student life, it's pretty good. Lots of events (balls, booze cruises, foam parties etc), lots of random on campus barbeques, every tuesday there is a free barbeque and band in north court, and sometimes they get great acts like tripod etc. The student life at any uni is probably similar, but I only know melbourne, and it's great.
Hope that helps.