We traditionally call them 'thongs', but they are increasingly being called flip flops due to the prevalence of American culture here. Traditionally they were worn with shorts, but people now wear them with jeans.
This is called a cork hat. Normal head movement causes the corks to swing around on the string, thus shooing away the annoying summer flies.
These people are wearing short pants which are called stubbies. Sadly, these have gone out of fashion for guys, who now seem to go for shorts that go past the knee. They are now only worn as work wear, say, if you are a plumber, carpenter, or crocodile wrestler. A more feminine version of 'stubbies' started to experience a comeback in women's fashion about 3 years ago.
'The tash' (otherwise known as 'the mo'). This is a very bushy mustache that men grow on their upper lip that continues further down than the Tom Sellick/ Lionel Richie version of the mustache. The top photo is the 'David Boon' (or Boony) mustache. The second photo is Merv Hughes mustache, which is typically grown even further down the face, breaching the jawline. Both are admirable. Note the guy in the stubbies photo (with the two girls, above) has tried to grow (a very poor version of) the 'boony tash'.
The 'Drizabone' is a type of oilskin workcoat that Australian farmers wear to keep them warm and dry in the rain. The name is a pun, meaning 'dry as a bone' which is what you are meant to be when wearing one in the rain. In my only experience wearing one on a geology fieldtrip, the rain always finds a way inside, and after a few wears, it would be more aptly named named as 'Smellslikeacow'.
In the above photo of the guy wearing the 'Drizabone', he is also wearing an 'Akubra hat'. This hat is great for keeping the blazing sun of your face and neck. Again, only rural people wear these hats, so just because they don't actually have 'red necks', thanks to the protection offered by the akubra hat, you can safely assume anyone who wears one is a 'redneck'. Akubra hats can be worn with the corks or without.