Wait a couple of weeks and get the new Apple iPad Mini Retina - make sure you get the version with the 3G/cellular option (about $600-$700).
Maybe buy a booster battery pack for extra power if there is no way to charge the iPad in the plane and you take long flights (maybe $30).
Get a Telstra pre-paid mini SIM card with a good allowance for internet data. (say $30 a month)
In the Apple Apps store get Ozrunways ($99 bucks a year for AirServices subscription) and NAIPS. (Avplan and AirNav Pro are other good alternatives).
Then you're set.