i have a friend who went through the first 2 rounds and was booted. he is quite smart too.
make sure your application sounds good, smart for that matter.
for the aptitude testing, etc, undertake a few courses to prepare yourself for those. word is they are extremely intense. i am not sure what is beyond this, however i do know one guy on the interview panel. he is a CASA ATO and is a pretty serious guy. make sure you know what you are talking about. (you might be able to guess, i scored him for CPL and IR flight tests!!!)
good luck