Hi Etty
One of the disadvantages of being classified as a active investor or developer is that you will loose the halving of CGT when you sell the asset as it will be considered trading stock and therefore tax will be paid at your normal marginal rate if an individual or at the Company rate of owned by a Company (A Company owned asset does not qualify for the concessional CGT Tax anyway).
Whilst certainly you maybe able to make a few claims in regards to expenses you really need to consider carefully before you decide to become a full time developer / trader.
Richard Taylor | Australia's leading private lender