Hi - coming into this convo a bit late.
I'm undertaking a KDR in the Eastern Suburbs at the moment. Using a mid size volume Vic builder who specializes in sloping blocks (I won't mention as they read this forum). The slab was laid about 3 weeks ago. Lots of piers too.
The power pit times sound terrible. I am in a UE area and got the pit done in Sept last year. I was fortunate regarding timing, as the quote was done within about a week (after I submitted my diagram) and the pit was installed within the fortnight of paying the install fee. My fee was $4200 for the pit and additional 16 metres of cabling (the standard pit fee in Sept '16 was $3370 which includes something like 5 metres of cabling).
Demo quotes vary significantly. I'm the kind of person who likes to research A LOT (including this forum), and get lots of quotes for all trades. I obtained 12 written demo quotes. The variance between quotes was around $10,000. Demolition isn't an exact science, and like all trades, they quote based on how busy they are at the time and whether they want the job. Some demo companies like to play games and quote high then tell you they can match a competitors price. Obviously get a demo quote which includes temp fencing, the demo permit, and the asbestos clearance cert. Apart from this, I would suggest going with the company with good communication skills and easy to talk to.
I obtained the asset protection permit myself from Council to save paying the admin overhead through the tradies. You'll need this before demo works start.
I assume you'll do the crossover swap and concreting after completion of the house? As I recall, for my Council, the crossover permits are only valid for 6 months, so you are better of getting the permit closer to house completion.
Any other questions (or recommendations), feel free to ask - perhaps via PM for the recommendations. I can't answer the questions on renting however, as we bought our KDR as a vacant house and never lived in it.