she'll be apples mate
it is not the least bit offensive, if it is held perfectly still. It signifies everything is A OK, a job well done, thanks a lot. It is a bit like the OK sign, the circled thumb and index finger.
When I was a little girl, ( myave things changed) if you held your thumb up like that and jerked it upwards rapidly....that was rude,ooowahhhh I'm gonna tell my ma on you( those were the days). But that was a long time ago, it is not considered the least bit offensive now.
regional accents/dialects? Australia is a very large continent with great big empty bits, a sparse population . Communities develop in isolation(less so these days) and with that comes localised language. The word "pearler" for example,I used in another thread is not something I grew up with. I picked it up a couple of years ago from a new friend I made. She said it, I liked it, I adopted it.As far as accents, I think there are. My friends from Adelaide accent imho.
One elderly man once said to me, you know the further north you travel on the east coast of Australia, the more the English language deteriorates. I grew up and live in about the middle...I speak cassperanto