Wedid a similar itinerary on Seabourn last Christmas and it was great except at this time of year is cyclone season in the southern hemisphere, hopefully you won't experience one as we did coming out of Townsville. Waves over the bow which was fun for a day or two. Mooloolaba is a lovely town but I don't know of any cruises that have actually tendered there due to the large swell that exists and tenders can't be used. Burnie is actually my home town hope you will love it as we did. Exmouth is another that is bit iffy we arrived there in very choppy conditions but the weather improved through the day and most people were able to go ashore. Enjoy Australia its a big country but the people are okay.