With a campervan from Brisbane to Melbourne Travel Forum

Hi guys!
I am not sure where to post this, I hope I will get some help within this thread. My girlfriend and I are living in Melbourne for one year, doing our Master in this fantastic city and are going to do a road trip from Brisbane to Melbourne, starting in two weeks.

I have some questions according advantages and disadvantages of campervans. Hopefully someone can help us out with some personal experiences...

1. Which campervan rental companies are the best? We know there´s Britz, Aussiecampervans, Qualitycampervans, wickedcampers and many more. For us it´s important to have a fully comprehensive insurance, even though it´s more expensive.

2. Which type of campervan would be the best option for 2 people and a travel time of approximately 4 weeks? We don´t need a shower in the car, but we would prefer sufficient sleeping space and at any rate a sink.

3. Does someone have experience with sleeping in campervans at night? We are worried about the temperature in the car. If it´s very hot outside, is it possible to sleep well inside? The air condition probably is not usable at night. Or is there an additional car battery included?

4. What´s about wild camping? Is it allowed to spend the night in the van at any place? Or is it just possible to park the campervan at specific camping/parking areas? What are the usual fees to park the campervan over night at specific camping sites? A shower now and then would do no harm... ;)

Thanks in advance for any suggestions. Would be very very helpful!

Regards,
Ben