0lancer0, I think their mini-interview in Stage 1A is setting the stage for the Stage 1B interview. Perhaps it is so they can quiz you further during the 1B interview, instead of having to use the time getting to know you. That is just my guess though, maybe we will get to know more after next week.
From what I've gathered, Stage 1B is a 45 minute JKI quiz (multiple-choice), followed by a 30-minute interview with a HR lady and pilot. I believe the test is strictly on material from the booklet, though a few questions on the company will be asked too.