As far as I'm aware most airlines will require EFBs to be in 'flight mode' while airborne, so the chance of seeing Ozrunways airliners will be rare, until they move into the modern era and stop using drums for advanced communication. As for how you address the unknowns, well, if they call themselves Crunchie or Arch, try that over the radio. If not "Traffic approximately 10 miles north of Flinton at 1000 ft what are you intentions" or something like that.... If center sees you on screen and need to communicate they will use your ADSB tag if no one answers a call, have heard them do it numerous times and pass on the tag information to IFR traffic to try to contact, with the provision it is just a squawk tag.