That is a good buy Clint. It is a struggle to get anything around $500k in Coorparoo now, especially, something that is sufficiently raised that it is legal height under the house (assuming yours is).
Illegal is probably a strong word, but not allowed is still correct.
Most REAs will call it teenagers retreat, pool house... But barely ever see it get called granny flat in Brisbane.
First, 7% is not strongly positive cash flow... Depends on lots of variables - rates, vacancy, repairs etc.
Second, Dual living on separate leases is still illegal in Brisbane.