How long and how safe is the drive from Perth to Cairns?

So me and three friends are coming to Australia and renting a car to drive across. We are planing to fly in to Perth, drive up to Carins and then along the coast to Sydney. Im just wondering should we be on the lookout for angry Aborigines, killer kangaroos, wacky wombats or the notorious Kelly Gang? Seriously we have gong on long road trips before but this one is going to be our longest and I just wanted to get heads up on the situation.