when you return from Australia if you want to stay long term you will need a visa. So why let the old one lapse and have to go through the whole process again?
Renew it for another year which you can do up to 45 days before expiry and get a re-entry permit which you can use to get back in when you return from Australia.
my banking app can read the QR code but it won't make the payment the electricity bill. It gets an error message. It's not the ability to scan because I don't even use cash anymore I scan everything I pay for.