The group assessment will involve a few group activities, a tea break where the recruiters will ask you some questions about your lifestyle and you are advised to ask them some questions about the role etc and then a written problem solving test which basically tries to work out how you would go working on your own.
Qantaslink interviews are hard to predict and from what ive seen of the people that have been successful its hard to predict what they want.
Good Luck.
I mist say though getting this sort of advice could hinder you at the interview, in my opinion its better to go into things not expecting certain things because you act more natural, and thats what they are after.