I applaud your enthusiasm and research so far. I think CharlieGolf's answer is the best suited. They don't expect you to be ready trained, least not from unclassified books.
Go more for current affairs, influential politicians/def minister, understand the current role of the ADF, develop your Ded Reckoning skills, study all aircraft types/bases/roles, and have a think about answers for the worst possible questions they might ask about yourself (e.g. why didn't you do so well at physics, or what happens if we post you to the IAI Heron?).