Us Aussies are generally laid back and have a tendency to not take ourselves too seriously. For instance, among males the words "old bastard" are usually a term of affection.
I wuold just clarify this with: its the tone in which it is said, more than the words. Pretty much any sentence can be uttered in affection as well as in dispute.
Yes, tone is everything as is context. Such as using the phrase "Happy birthday, you old bastard" is perfectly acceptable among friends.
Other terms for your amusement:
Cheers = thanks, when used I'm the context of thanking someone. Usually informal,y thanking a friend or colleague.
Bloke = older male, though the equivalent for females (Sheila) is generally not used except maybe in rural areas.
She'll be right/she'll be apples = all is well or all is going to be well. Similar is "no worries" which is the problem you have is nor worth worrying about.
Fair go = shorthand for "you're not being fair to me and/or someone else and you should be"
Too right = an expression of agreement
Shout = to buy someone a drink and/or meal. It's both a verb "I'll shout you dinner" and a noun "it's your shout"
And my favourite, which is hardly used anymore "flat out like a lizard drinking" which means extremely busy.