I personally hate it when a passenger needs to be rebooked, and they stand at the counter telling me that Expedia shows a flight I should put them on, or suggests routing to me. Believe me, most agents already know the applicable routings and for OP, there are very few that will work. It is annoying and distracting to have the pax shouting out instructions while I'm trying to work.
Uh, no. You are not rebooked at a priority because you are on vacation. Usually in IRROPs, there are lots and lots of passengers who have to be rebooked, and very few seats. I wouldn't hold my breath for this routing. There are often weight restrictions on Australia flights, and they frequently don't go out or return with a full load of passengers. Anyone flying in the day of the cruise to Australia really should rethink this. Very bad idea.