Driving Perth to Brisbane via Adelaide - I need advise please!?

Hi, I am planning to drive from Perth to Brisbane with a few days stop in Adelaide (from what I can see, Adelaide is on the way so I figured we'd stay there a few days as I have never been to this city before). I've not ever crossed the Nullabor, or driven on any of the road between Perth and Brisbane for that matter. I am hoping to do it over a week, so with 6 overnight stops altogether. I know this will be a push but I would think it is doable? Can anyone please advise where would be some ideal places to stop for the night across the Nullabor, and should I be booking in advance or is it fine to just book into the first place I see before sunset? Also - what is the general cost of accommodation over the Nullabor and for the drive from Adelaide to Brisbane? I have a Mitsubishi 380, great condition but it is a sedan car, not a 4WD with bullbars, will I be ok doing this long journey in a regular car? any advice about this journey would be greatly appreciated, as I am a bit lost on where to start looking for information or how much things cost, if I am crazy thinking of doing this in a regular car etc. I only plan to drive during day light hours for safety reasons. Thank you in advance for your replies :)