M`lad,a few points to ponder;
1.No idea,but a good start would be a lot of self-motivation,lateral thinking/problem-solving,a fierce determination to succeed,and knowing everything about the job and the RAAF.
2 As much or as little as the Service demands.
3.No idea,but take the point that others make.
4.Don`t know about RAAF,but they are not there to support `camp-followers`,unless you are married(depending on Rules),so your pocket will take the hit...
5.Ditch Sheila before she ditches you,otherwise you`ll maybe get a `DJ`,or a `text` when least expected,ie during training,exercises,possibly a `War`,or whatever; saves paperwork.
At your age(19),you should have motivation to be the `best`,and willing /able to accept what is thown at you.Everything else takes second/third...Remember,it`s easier to rent a `car/bike` for a day or two ,than to buy one....