re: International Insurance?
This should be covered by the institution that you do the student placement through, e.g Sydney University. I would contact the student placement co-ordinator to investigate this further. This was the case however for me when I (then an Aussie PT student) did a rotation in Canada through the Uni of Alberta.
re: International Insurance?
The way I did an overseas clinical placement was via an exchange of placement positions with a Dalhousie University in Halifax, and students from there have come to Australia. By doing it this way you should be able to have you insurance organised via the University, so as already suggested, best to contact clinical co-ordinator at an Australian university (The two physiotherapy schools in Melbourne are La Trobe university and Melbourne University