Hi,
As far as I know from my friends that economy of Australia confronts sever difficulties that make it makes hard for international students to get jobs. Besides, I heard the Australian authorities make it hard to get work permit but I do not exactly the requirements. You need to consult someone, contact the MGSM directly or review visa regulation after graduation. check the following link
https://www.border.gov.au/Trav/Visa-1/485-You do not need to take the ranking in that way. Ranking is for guidance. They have certain metrics that may make university higher than one. You need to search the best within the same country where you target ending up living and working. The international recognition is different for region to another. You maybe graduate from best school in Australia but it can't get you to any another pace except Australia. The same works for Canada. So if you target Canada, I advise you to search within Canada. You can search in our forum here about students who applied to Canadian schools. In FT 2016, there are 3 Canadian schools vs 3 Australian.
Good luck