I realise that, I am going off the one time we were moored at Athol Bay, out of the way from the ferries, in any case it doesn't matter where it is exactly as it is still a 15 minute tender trip to the docking point.
If you have been in contact with any lake's or fresh water streams answer yes, temperature wouldn't matter.
Definitely wash your swimmers, etc.
The best thing to do is answer honestly, it may mean further questions, but that is much better than a fine or worse breaching our biosecurity and bringing in a bug or pest that may destroy our ecosystem or an industry.
Busselton is a tender port, and you can walk into the main area. Albany has a dock but it still may be a tender port. Either way you may not be able to walk off the dock, they will likely have shuttle buses but it is close to town,
Which ship are you on?
I was on a tender by lifou once, it broke down, we bobbed around and difted for ten minutes waiting for help. Instead of towing us back to the ship or to the dock, we then had to be moved onto another tender. It was a prolonged experience as we were bobbing around. The second tender then ran out of fuel. We were towed back to the ship by a third one.
I would still do both and just do the walk around the town and shops.
Airlie Beach is likely a 20-25 minute tender ride, it is a relatively easy walk into the main town area although there are also cyclotour people that can ferry you into town if you don't want to walk it.
For Yorkieys Knob, the tender ride is close to 30 mins and then there is a 25 minute shuttle bus into Cairns. That may be the one you want to miss.
I once found that I couldn't make a purchase in Argentina, I didn't have enough pesos, I didn't want to use my Visa card due to fees, I offered USD but the exchange rate they wanted was horrible, so I walked out. The next day, they saw me walking past and offered me a much better rate. It was too late, I had found another shop.