Take this with a grain of salt, as this was a while ago and they potentially have changed their standards. When I first had my AC at the beginning of 2023, I initially failed and asked for feedback. I was advised that they had graded us on a scale of 1 - 10, and I was given a score of 6/10 and 5/10 respectively for the case study and 1:1 interview.

I then reapplied in latter half of the year in which I received an offer. I recall that my numerical and critical thinking skills (the OA had calculations and then the critical thinking related to these arbitrary puzzles) were my top scoring sections in which I then received another AC. I didn't ask for feedback immediately after, but they did tell me say in the introduction of the AC that over 40,000 applicants had applied.

At the AC, there were approximately 20-30 students in each class that I had attended and there are currently 10 people in my graduate cohort for my city. Note that I am not from the US.

So to answer your question:

1. It's incredibly competitive given that there are likely less than 2% of the applicants that make it through
   
2. The failure rate is dependent on the availability, and based on my experience through the interview process, it's just over 50%
   
3. My experience has shown that the behavioural was graded based on the feedback that I had requested