I recently purchased a vehicle that has no stereo installed. The speakers and antenna are there, but no head unit. As far as I know, there is no amplifier, either.

So, I wondered if I couldn't develop a custom wire harness to incorporate my iPhone directly into the speaker system and allow me to charge it and listen to music while I drive.

The car supplies power to a stereo system via 12VDC. There are two circuits on the vehicle's connector that supply 12VDC from the battery and 12VDC from the ignition. To charge my iPhone I will only need one of these, correct? I'm assuming that a charge straight from the battery will be sufficient.

There are 2 12VDC pins in the iphone connector. According to pinouts.ru they are both +12VDC. So I would need to run the 12VDC from the car to these two pins, correct?

Also, the vehicle's connector has one ground circuit. Should I simply tie all of the iphone's ground pins to this single ground?

As far as the audio, the vehicle has no head unit and I'm assuming has no amplifier. Will I need an amplifier?

The vehicle's connector has a separate circuit for each of the four speakers (2 right, 2 left). I'm assuming that I will need to tie both left speakers together and both right speakers together for the iPhone's connector.

Thanks in advance for any help anyone offers. I'm an electronic assembler, but I only have basic knowledge of electronics. I'm pretty confident I can perform the work, I just want to be sure that I won't blow up my iPhone or waste a lot of money doing something that won't work.