Hi,
You can choose most existing properties that you wish either, residential or commercial, you don't have to build. The negative gearing shortfall between the rental income and the interest and other costs should be balanced each year via Super Guarantee Contributions by your employer. If there is still a shortfall you can salary sacrifice an amount directly into your fund to make up the difference. There is a big tax saving here for you.
Also, if you want to pay the Principal off the loan, you can salary sacrifice a further amount. In doing this you will accomplish what no other geared investment can do and that is pay Principal off a loan and get a substantial tax benefit for it.
You do need a 20% deposit on the property plus stamp duty and legals so you will probably need a minimum of $120,000 in your Self Managed Super Fund