Okkies working in australia can get you some good money but you have to research when and where you go with the seasons of the crops. My hubbie (american) and i (aussie) traveled around oz doing this and some days you could bring in $200 a day each (top dollar on good day) other days you bring in crap. Some years the crops aren't so good and others it is and you must know when picking seasons are and travel with them. Getting the actual job is super simple though and yes some companies will let you stay at their logde for free or discounted rates. Just talk to the man in charge (have good people skills).
Now getting jobs at bar staff and waiters is pretty easy in the cities. All you need is some experience. And you can also get jobs through hospitality agencies (pinnacle hospitality, zennith group are a couple of them in Brisbane) Basically you work for all different companies when their staff are away or sick. This work also fluctuates with the seasons, summer busiest. You can also get work at hotels as bar staff and dish pigs and get free accomodation, all you need to do in bring a resume and talk to the managers and they are ussually pretty reseptive.
If you like Australia too much after all that you are going to have some problems staying. It's super hard unless you just overstay your visa. But this is illegal and anyone can ring with just your name and you'll be booted out of australia. Most companies will NOT sponsor you unless you are critcal to their team. Ussually meaning someone high up the ladder with uni degrees ect. You can extend you stay for a little while depending on what visa you got comming in to australia. If you are getting a regular visitors visa with no work visa permiit and they find you have worked you'll be chucked out. also you can't change from visitors visa to working visa inside australia. I you have a working visa you may be able to extend it for 3-12 months depending which country your from and how long you can over in the 1st place.
Bascially apply for the longest working visa from your country and enjoy australia, then you may get an extension if you want to stay a little longer, but nothing can help you much if you want to stay indefinitly. It's super hard as I know trying to immigrate my husband over here from america and costs thousands of dollars.
HAVE FUN AND GOOD LUCK!