sandshoes without socks - old fashioned white tennis shoes with a canvas upper and rubber sole - not the fancy-dancy Nike types of sneakers.

a cream weatherboard (house) with a green front door (weatherboard) - a weatherboard house has long horizontal planks of wood on the outside, which is usually painted a lightish colour and the trim, e.g. window frames, door frames, gutters etc would be a different slightly darker colour with the door painted usually a darker or brighter accent colour. Three colours altogether.

he reversed quickly, skittling a rubbish bin (skittling) - skittles is a backyard version of ten pin bowling. Smaller pins, smaller ball, used mostly by kids. So to be skittled is to be knocked over quickly and spectacularly.

ugly mega-churches and businesses for cashed-up bogans (bogans?) - possibly the nearest U.S. equivalent would be trailer trash. A lot of hoons probably belong in the bogan category as well. Hoons would be cashed up enough to afford a car. Some bogans have come up in the world but are still proud of their bogan origins.

the Catholic op shop behind the Coles parking lot (op shop, and by the way, what kind of place is Coles?)

op shop = opportunity shop, charity shop, thrift store, usually specialising in used clothing and kitchen ware.

Coles is a national supermarket chain on the same scale as Woolworths.

young, bright, up for a stoush - a stoush is a fight, usually physical but usually involving a lot of shouting too. If you are up for a stoush you are actively looking for a fight.

"We were on our way back and we saw a booze bus, and in a panic I hid the gun." (booze bus?)

Booze bus is the Police Force's Random Breath Testing (RBT) mobile van. They set up on roadsides and pull drivers over to test for alcohol i.e. booze on their breath or drugs.