alisonld
Though there are a few threads on education issues, some related to private Vs public the forum is a relatively youthful one and given the length of time it can take for skilled visas to be processed, it is unlikely that any earlier participants here will have actually got to the stage of actually being Australia to enrol children in schools.

Sadly, with the odd exception, not many people do come back and reveal their experiences and I think you can find that is a trait of many forums and then those that have done it in the past may not become members of forums like this one.

But in general terms seeing as you'll know a fair bit on education being a teacher yourself, I would not imagine our schools systems to be too greatly different from other countries and the various influences that can exist.

In regard to how you handle it for Australia and your daughters, if it was me, I'd be doing some planning along the lines of:
. Looking at all the information on where you feel you might want to reside in Australia, ie Climate can determine state, and then all states have capitals as usually having the greatest choices of schools but then regional living can have its benefits in peacefulness, lower costs and closer to nature either coastal or inland, and thus review whether school/later college or university options in smaller cities/towns would be adequate - do the daughters have any careers in mind already?
. A skilled application could see a result occurring no earlier I'd expect than near the end of 2009 and quite possibly sometime well into 2010 dependant on path you choose, and then you need to look at best timing for your move in respect especially for the older girl and school year calendars, ours running from January/February to November/December and how if your older daughter is nearing end of her secondary schooling as in last year of secondary schooling you could I can imagine imagine yourself that it could be disastrous in pulling her out of a final school year half way through and not only cope with picking up another countries/states/schools syllabus but also being on an equal footing in grades being considered for tertiary entry; the final years especially of secondary school may differ from state to state and I would check that with state education departments - for instance I know quite a few years back that the state of Victoria secondary schooling was structured on a final two years combined assessment called CATS (can't remember what that stood for) and it is quite possible that it may have changed and now at a Federal level, new Labor governement is talking up the education revolution we have to have and be interesting what impact teachers unions might have on it all as the teaching profession in Australia has developed something of a political left lean.
. So having projected what may be your best move time and where, if you're going to opt for private schooling you'll need to make enquiries in advance with schools in regard to their capacity and process for enrolling, that for state schools being more along the lines of having the right to enroll a student at the closest school.

So, hope that helps.