My first concern for Australia is that it should be under Oceania, no Oceana. Not a good start. Site generally full of typos.
Thumbs up is not obscene.
Inverted Victory isn't really much of a thing. Understood to be rude but rarely utilised. Not sure why 'rude', but middle finger designated as 'obscene'? I'd say on par with one another.
NOT common to bring own beer to restarurant. Wine in common in some venues, beer very unusual everywhere. Either way dependent on venue licence. Should advice that a corkage is almost always applicable.
I'm full = utensils on plate. Should note utensils face up.
Also - bar tipping, alsmot everything in the USA section applies to Australia also. unsure why that detail not included. Except knife down. Aust/NZ/UK don't do that. We're using that knife. But then we don't swap hands to use fork.
UK almost entirely applicable too.