Hi Scott,

Our school holidays vary slightly from State to State, but generally speaking are from the last week of June to mid July, so you may want to keep this in mind when you're planning your Cairns/Port Douglas time.

I think you've made a great choice in locations and with a vehicle, you'll have the freedom and flexibility to really explore at your own pace. Driving "on the other side" is easier than you might think, although it does feel a bit weird for the first half-hour.
Then you settle into it. Of course, you'll indicate your turns with the windscreen wipers - just as you do when you get into a rental car at home (LOL).

If you can factor in another couple of days, I'd encourage you to have a look at Alice Springs & environs when you're in the Uluru area. Have a look on the www.travelnt.com link
I spent a fortnight there a couple of years ago and thoroughly enjoyed it. I posted a bit about it a few weeks ago - click on my name & it will be amongst my posts. Watching the Birds of Prey show against the bluest of blue skies in the natural ampitheatre formed by the orange red cliffs in the Desert Park is one of those goosebump experiences.