Some advice please...

Hello all,

I am a British citizen, married to a Thai national and we have a son together. I lived in Australia from the age of 12 - 26 untill I came to Thailand in 2001. I had perm residency status when I came then. The perm status visa expired but in 2009 we all applied for perm status for Aus, got it and we all went back for 3 years while I finished my studies......Fast forward to today and all of the perm res Aus visa's have expired and we want to go to Aus for a holiday during the Thai school break. 

Now, both my sons Thai/British passports have expired and so has mummies Thai passport. My British passport is ok. I am wondering what is the best course of action to take. For me getting the 'E' visa or whatever  its called seems pretty simple. I am wondering about my wife and son. If they both renew their Thai passports will it be much of an issue to get them tourist visas? Keep in mind that I would be going there as a British citizen...no advantage of perm residence. My wife is a teacher, she has a VERY stable job and its been this way for years. I assume she will need a letter from her employer. We will be staying at my parents house most of the time. I assume a supporting letter from them will help our cause. 

We have limited time to sort out passports. I may also be going alone ahead of my wife and son. I would prefer they both stick together and not have separate passports while going through all the immigration rigmarole at airport in Aus...May seem silly but I want my wife and son NOT to be separated at any point. 

The fact that we all HAD perm res status mean anything? Does it really expire? 

Any thoughts/advice would be greatly appreciated.