you'll be able to see who's around without radar.
No.
1. Unlike the USA, Australia is implementing ADS-B out only. The units have no ability to receive data.
2. VFR, RA(Aus), ballon, glider & historic aircraft will remain using mode C or will have no transponder at all. So, Ozrunways or any other non certified cheap thing will not see this traffic.
All of the mid-air "frights" I have on IFR plans had have been VFR aircraft or aircraft with non functioning or non-existent transponders. Not one of them would have been made better by my spending $25k on upgrading to ADS-B. This includes an instance of a conflicting direction same level VFR aircraft while I was in IMC!!
There is no benefit to GA IFR aircraft in class G airspace from the fitment of ADS-B
Australia is the only country in the would that is mandating ADS-B for all IFR aircraft in all airspace types at all levels.