To be honest I'd rather it be two just to write more. I always end up with a ton of time left so I want to write the full 5 paragraphs I have planned haha.
I reckon one. From what I've seen it's been holistic(Either "at least ONE" or "TWO") quite a bit in previous years so it may be specific to only one year.
Could you not calculate weighted internal assessment averages for the top students and determine ranks that way? Thats what my school did for certain subjects prior to ranks being officially announced.