Hi, it's difficult but it's early days. I too am a midwife, I moved with my family to Sydney in Jan 2014, so barely here a month and one thing I've realised so far is that it ain't going to be easy, it's going to take time to settle and along the way there are going to be many obstacles thrown in the way. But I think the key is to remember why you came in the first place?
With regards to PR visa, I'm sure there will be a way and a good agent will definitely help, will your wife's employer sponsor her for PR?
Where abouts in Sydney do you live, maybe other forum users may know of appropriate schooling for your boys, I know finding the right school is such a worry and the fees don't help on a 457!