First of all, are there any Non-Stop flights between SLC and Australia?

Next, assuming a connection of some kind (because the answer to the first question is no), which airline did he take? Which hub will that flight fly to?

Let's assume that the flight was on Quantas (logical), the US Partner to Quantas is American. How many times/day does American fly non stop to Salt Lake? Could he have taken Quantas to DFW and then Non-stop from DFW Could it have been through SFO? Could fly in Quantas and United (less common, but happens). Many fly that way through United. Could have been Delta through LAX, but Delta flies like 10x/day between LAX and SLC.

Sure, just call the airport.