I would be very wary of Leave of Absence (LOA) from QF.
The devil is in what the letter of agreement doesn't tell you.
Insist that they still contribute to your super, loss of licence and that you have continuity of service.
Who pays for your requalification on return? Do you have to exhaust leave before you go etc?
Years down the track a little LOA can rear its ugly head and affect long service leave, sick leave, super, redundancy etc.
Tax is always an individual responsibility; even though you may have right of abode in EU the Oz ATO has onerous residency requirements.