No USB port, can you charge iPhone while playing through AUX?

The iPhone was designed as a music player as one of its objectives. It will play music longer than it will allow you to use it as a phone. All day music listening versus 8 hours or so of talk time. So the answer is, yes. 40 minutes through AUX will hardly affect the battery.

I've always heard interference when playing music and using the 12V on my other vehicles. I've had no need to do it in my Prius so I don't know the answer. I do know that the interference is minimal on my other cars that I could easily ignore.

~3GB is taken up by the OS. Is ~5GB enough for a music collection? I play music through the cloud so I don't need any space. Others say 64gb is limiting.

 

The battery drain playing music that is on the phone is minimal as long as you have the screen off. If you're streaming with an app like Pandora, though, it'll drain quite a bit more. I would just keep a charger at work and charge there if you think it'll be an issue.

 

You can buy a 2-in-1 charger and audio cable like this one on Amazon:

Amazon.com: Kensington 2-in-1 Charger and Audio Cable for iPhone/iPod, including iPhone 4S (Discontinued by Manufacturer): Electronics

I've owned this specific charger and it worked great with our iPod.

 

I would try this bluetooth adapter for the best solution...handsfree talk, music and siri integration.
All automatic and no wires!