I was using that setup in my old car...but I got a new car in July so I'm not using this anymore (it has built in nav). In the old 2002 Camry, I had a OEM deck with a cassette player...so I used a job that cassette adapter on one end and a 3.5mm stereo connector on the other. That 3.5 mm stereo connector when in the headphone jack of the iPad. So this is how I got music, audiobook and Navigon to all sound through my car's speaker system (I always get the top of the line audio in any car I buy because I think it pays for itself over the long run -- though, in my younger years I would install my own, but I don't enjoy that anymore).
As a mount, I used one that comes from Arkon. This one:
Amazon.com: Arkon TAB-FSM Tablet Seat Bolt Mount: Computers & Accessories
attached on the passenger side. While the arm is quite strong, the iPad will tend to vibrate when you pass over bumps in the road. So I used a form block I got from the box of some other piece of electronic gear I bought...adjusted the holder to put the iPad close enough to the dash that I would wedge the block between the two...this zeroed out most of the vibrations. Keep in mind I only used this on long trips.
I used a 12v car charger that supplies both 10W and 5W on a usb port. Using the 10W port, I could keep a charge on long trips...Others have found that the iPad 3 would lose charge on long trips. I think this is a function of 1) your brightness level on the iPad (you need brighter in the daytime) and 2) the charger used. It could also depend on whether you're using bluetooth and LTE. Since I was using Navigon, which has it's own maps installed, I didn't need to use cellular. I also wasn't using BT in that setup. I did the same with my iPad 2 and never had any issues with charging, though.
I'll see if I have any more detail pics later today and if so I will post them.