Brand name for commercial 'yellow cheddar' - aka 'rat cheese' - made by Kraft Foods. In this case, it's supposed to refer to a US 'frontier' tradition of a general store keeping soda crackers in a barrel, from which they are sold by weight. Supposedly 'country'.

There are way more cracker barrel cheeses than mild yellow cheddar. At least, in the US there are. Their extra sharp aged reserve cheddar is actually good.

Yes, but the questioner specifically noted being in Oz - not in the US.