Welcome to AFF
@Andykay .
I’m sorry, I’m not going to address your particular queries except to say that yes Platinum by far gives you the best chance of securing Qantas award flights.
What I want to say is: are you determined to go down the Qantas frequent flyer path, If you are going to churn credit cards.? There are ones where allow you to accumulate points on programs like Singapore Airlines Krisflyer. There’s even a star alliance. branded card these days. See the thread on this.
Qantas frequent flyer is notoriously difficult to get flights to say North America or Europe in premium cabins, and this was a thing well before Covid. Even flights to places like Singapore. There are many people who have huge amount of points and simply unable to use them for booking in premium cabins.
So, before you commit to Qantas frequent flyer, just consider all the alternatives. This forum’s as sister website, Frequent Flyer Solutions can be of great help in looking at the alternatives to Qantas FF. At the very least, google that, have a look at it, maybe subscribe and check out some of the highly informative expert commentary, webinars etc.