I live in Melbourne but looking to stay at GH this New Years eve to watch the fireworks and hang out in city

I am a Diamond member and will be using points for this stay.I know if using points PH is a better option as you get the club deluxe room which is larger (which matters to be as I will have 2 kids with me) however PH will be far away for New Year celebrations

My questions are

1) What size room can I expect as a diamond especially on this night?
2) Should I look to pay for this night and use my suite certificate (which are expiring in Feb and I have no use for them)? Considering the night, my guess is suites will be paid for as well, hence my guess is my chances are less
3) What benefits can I expect as a diamond member?

Thanks