hi Sarah,
I came out to Australia 12 years ago so can't help you too much on the visa and house front. I'm living in Airlie atm but due to move to the Sunshine Coast next week. Looking at renting in Buderim (loved the area) until we settle then look for somewhere to buy.
I have two children (ages 9 & 7) and they also have been in the Catholic school system here. When we went to visit Sunny Coast and looked at schools, we liked Stella Maris Schhol in Maroochydore (Prep-Year 7), so we've enrolled the boys there. There is also Sienna Catholic College (Prep - Year 12) both schools have a good reputation. There are a few other catholic schools too, I think there's one at Currumindi, and one nearer Noosa.
Good luck with everything!
Kate.