Fair call.
While I never tire of whales or dolphins when out on the water, a trip up to Lady Musgrave a couple of years back (sailing around the outside of Fraser): we got to the point where we stopped pointing out breaches, the were so many.
It is pretty good seeing them close to home though. Every year, I'll see a few wander down into the bay - as far as Coochiemudlo.
Here's a juvenile, with Coochiemudlo in the background, from a few years back:
I don't think you can easily get a SIM prior to travelling (unless your phone supports esim).
However, this guide provides you with info on where you can buy Sims at various incoming Aussie airports - Sydney is first on the list. Boost (as per comment from @tuff_wizard ) is in the list.
https://www.phonetravelwiz.com/buying-a-sim-card-at-sydney-airport-australia-guide/
Yep, Navionics and windy are where I tend to start, but the two that I tend to spend the most time in while route planning are Qtvlm and OpenCPN.
Qtvlm's route planning capability is pretty good once you get into it a bit.
Sunrise.
Horizon angle was a bit whacky.. but came out ok in the end.