We went this way last year as well. ATL-NRT-CNS-SYD. We didn't need any visa for Japan, but you do need the ETA for Cairns and they asked for the confirmation number as we went through customs.

I would highly suggest you have all your ZED/ID90 fares purchased before reaching Japan. We needed one additional one for the NRT-CNS flight and it took the gate agents at NRT about 2 hours to figure it out and give us one.

This way definately beats coach all the way from LA.