Google "Qantas Where can I go". It will take you to a website where you can filter available classic rewards in business class from your home city on any given date or month.

It is probably an oversight. Take advantage while you still can.

A security guard always stands at the start of the express lane. I showed him my express pass that the check in agent gave me and the guard let me through. The express lane will probably save you no more than 5 minutes. If you have to wait and queue to collect an express pass then I wouldn't bother.

I can confirm that classic reward flights do count however there is a catch. The catch is that you have to be a Points Club member.

No, there is no clear pattern to the last 5 times they offered the 30% discount.