You would be better of with 10 days, anyway there's a direct flight every day from Sydney.
Xmas time is awesome, sunny, warm, windy (regular 15/20 knts) and not hectic at all cause all the locals go to the gold coast at that period.....
(surfers paradise is our number one destination).
No jellyfish or sharks or crocs, just the odd sting ray....

As I posted wind has been sooo strong this week, yesterday a kiter went missing, the helicopters had to stop searching for him at night.
Apparently they found his gear but not the bloke.... sad...