1. If the flight from SYD doesn't delay, there's enough time.
2. By CI's rule on the website no, but you can ask the agent at SYD nicely and usually they will do it. If they don't you will likely need to head out to grab your bag (it would take about an hour to get that done and back to check in counter upstairs) or look for transfer desk and see if they can grab your bag for you.
3. No.