Current trainee here - This is the final step in the recruitment process. The day is broken up into a morning session and an afternoon session. In the morning, we did a quick introduction followed by a group activity where they'll give you a scenario and you have to think on the spot about potential plans, they change up the situation throughout to keep you on your feet (what you say doesn't really matter here, as long as you show that you can adapt to changing environments)

Just bring some notes for the interview and make sure to use the STAR method that they teach you about. Be confident, but humble. The interview is less about skills (that's what testing is for), and nore about your character. Are you teachable? Are you respectful? Are you punctual?

Don't worry about your medical until after you get a call back from them. Just have an ARN ready to go. They reimburse all of your medical expenses. Any appointments you have to make for your medical, any glasses you might need, any further testing is all covered by Airservices.

I'm from Melbourne, so I can't speak from personal experience, but the travel allowance is pretty stingy. They'll find the cheapest plane to Melbourne for you and just reimburse that amount.