C’mon guys cut them some slack. When they said “stressed” they probably mean “nervous”. Everyone one of us was nervous before going into an interview for an aviation position. They’re still young and in school and haven’t had much exposure to the world of Aviation.
Mate, they just want to see that you have an aptitude and drive for an aviation career. You’ll probably need to show some examples of good teamwork and critical thinking skills and situations where you’ve put them to use. Along with good communication skills and are well presented and prepared. They probably won’t be quizzing you on Aviation theory so no real need to study up on that. Look at some of the personality based questions on the cadetship threads, the questions you’ll get asked at your interview are probably similar.