Very happy my suggestion may be helpful!
Those foil'ed models are incredible! I think I may finally take the plunge and try foil.
Airbrushing - there are many books available about how-to. There are even some tutorials here on KitMaker; here's the first feature the site hosted: Airbrush Basics
The site has many talented and experienced airbrushers and there are many discussions about it. Instead of telling you to pick through 1,000s of threads, you could post a thread asking about it, or write me back and I will tell you of my 40-year experience with airbrushing.
How close are you to New South Wales? Here is a gentleman who is very good at airbrushing and may be of help, too: http://railroadmodeling.kitmaker.net/user.php?op=userinfo&uname=lesrogers
I may not get to reply to you for a few days (traveling) but PM me (the message button below my name). We'll get this sorted out.