Hi Dex.
An individual assessment is what is probably ADFA speak for what uni's call ROC, or Range Of Criteria. You'll probably be asked to take some written tests, have an interview (or three), they'll look at secondary and tertiary reports and grades. My advice for these sorts of things is just be yourself -even if you don't think you're quite right - because the moment you start bullshitting its very easy to tell - the people who interview you probably see hundreds every year.
You will have to approach ADFA about the PRK issue - I had a mate who went through RAAF screening and was told the whole way through that his corrective lenses wouldnt be a problem. He flew through the tests with exceptional scores and then failed the medical - for eyes. So there may be some inconsistencies there - just check it out with them
I'd also recommend that you maybe try and do some flying in the meantime - at least up to GFPT or even PPL level. I say this for two reasons. If you don't like it, then you can not worry so much about doing ADFA! If you do like it, (which is the more likely outcome), you'll have another string in your bow when it comes time to sit down in front of those interviewers.
Remember to though that RAAF pilots dont actually fly heaps - depending what Sqdrn and type you're assigned to it can be as little as once every two to three weeks! The rest of the time you'll be doing ground school or drills and other kind of... boring stuff.
Anyway, all stuff to think of and mull over.
Soft landings
Pete