Hey /r/Travel

I, am travelling to Australia in June for a full month, and was looking to pick your brains regarding certain aspects. I will be flying into Broome and spending 2 weeks there with a friend. We will be staying at his apartment, and will have access to a car. We will then be travelling down to Melbourne together, and spending two weeks in Victoria in a hired camper van.

We have planned out most of our time in Broome, as my friend has been living there for 5 months now and has become familiar with his surroundings. We also have some ideas for our time in Victoria, but nothing is really set in stone.

My main question is regarding money for the trip. I have read a lot about how expensive Australia can be, but my friends seems to think it will be rather cheap for us, since we already have accomodation, etc. Would any body be able to provide an estimate on general living cost in Broome for 2 tourists, living mainly off of home cooked meals, with some treats/eating out every now and then for 2 weeks. Most of our activities we already have planned involve going out with friends he has made while there. So hopefully most of this will come off quite cheap. We do however have a trip to Karijini planned, and was wondering if anyone would be able to provide a general idea of petrol costs for a return trip to Karijini from Broome.

The other question is about things to do while in Victoria. We only wanted to spend 2-3 days in the city maximum, and would rather spend more time at National Parks, etc, while in Victoria, but are open to any/almost all ideas. I had an idea of spending the first 4-5 days heading West out of Melbourne towards Otway National Park before heading back to Frankston way to possibly meet family we have there. After that we were looking to head East towards Lake Tyers for the next 8-10 days. Again, this plans arent concrete and we are always up for ideas.

I am sorry to burden you with these questions, and hope I havent been too vague in my descriptions.
But many thanks in advance for your response.