I would hazard a guess that it he is Army, because you can just see the "Rising Sun" badge on his collar - and I don't think, but am not certain, that the RAAF wore that badge in WW2.
Just a quick question, have you looked for service records at www.naa.gov.au, you are able to request copies for a minimal charge (compared with other countries) and will probably find answers to other questions you may have.