I'm no expert but  im my experience you will need to pay council rates, depending on  what services the land has, ie sewer, town water  etc…if it isn't a huge block and it has neighbours you will need to have the grass cut-  you may have to anyway as long grass is a fire hazard.
My inclination would be to  build on it if it is in  a reasonably populated area to get a rental return.  The only time i wouldn't is in a particularly low Socioeconomic area where you wouldn't want to rent it out now but believe it will go up in hte future (eg if it right on the water).

if it is your only property, then you won't have to pay CGT.  If you own other properties at the same time you may have to.  There is a questionaire on the ATO website that might be helpful to have a look at.

Have you thought about building on your land?  Rather than forking out for a new property it might make better sense to get some rental income off your land.