It is Australia rather than Austria.
I suspect that the Uni will have a good deal on health insurance for foreigners - they generally do - as an Australian, I really don't know how much these sort of health insurance products normally cost, as they are for people trying to access our health system, which we already have access to. We have a lot of international students in Australia, so I would also think that the Uni would have a ton of resources for you - and they are likely to be mustachian resources!
Brisbane is quite warm and has very little temperature variation. When I lived there as a child, I only had one winter jacket. It does get cold occasionally, and is having a cold week this week. It is also located near a lot of World Heritage areas - the Gondwanaland forests are to the south west (fifty separate reserves totaling 366,500 hectares (906,000 acres)), and Fraser Island to the north (world's largest sand island) - both can be reached within a day trip if you push it. There's also the Sunshine Coast and the Gold Coast. It has mosquitoes. It is subtropical, so when it rains, it buckets down, but it doesn't rain that often. When you go to the beach, make sure you swim where it is patrolled, so you don't have sharks, rips or blue bottles to contend with.
If you think European cars in Australia are expensive, you will need to get an expensive car. I think most similar cars are similar prices, whether they are European or Asian. We may or may not still have our own car industry, so everything is (or soon will be) imported. Australia is a food bowl and exports a lot of food, but we are a fair distance from everywhere else, so although we don't have much in the way of tariffs, things like cars tend to cost more.
I'm not sure about Brisbane AirBnb - some places in Australia have things against it if you are renting yourself. But I don't really know anything about this side of things.