If you are a permanent resident or citizen then you can buy any property / land in Oz you like.
If you are not a
PR or citizen then I have been informed by Melbourne EA that there are restrictions in place so that you can only buy off the plan properties.
I bought an apartment on 471 LB in Sept 2006 which is on a long term lease to the Mantra (as was Pacific) hotel chain. I get a fixed guaranteed rent paid into my account automatically every month with no deductions whatsoever (water, rates,etc) as all are paid by the tenant.
The rent is increased 3% everyother year, by the RPI the other years with rent review's every 5 years.
For an initial investment of $337K I am now getting around $25K pa guaranteed net before tax.
I can't help on the mortgage front as I got one on my UK house to pay for it in cash.
There are several apartment blocks in the Melbourne CBD with a similar arrangements which I would recommend you consider if you are going to buy an investment property.
At current levels you be paying a price that would generate 6-6.25% income net ie $333K cost, $20K rent.
If you have an employment history of 6 mnths with a good salary & decent deposit (15%+) then you shouldn't have any problems getting a mortgage IMO.