Arduino Pro Mini - RAW pin?

Hi!

I'm working on a new project for my car, which have iPhone interface in it's car stereo. Problem is I don't like the iPhone and the buttons on the in the car can't control Spotify.

So my plan is to connect a Arduino Pro Mini to the iPhone dock in the car and when it receive a command in sends the correct command to my Android phone that streams the sound to my stereo through bluetooth A2DP.

Do you guys that would work?

But my first question is the Mini Pro has on regulated 3.3v input and one RAW input. Can I connect the RAW pin and Ground to the 5V output in the iPhone dock or will I break something?

Why not take the iPhone 5V and drive the VCC/5V line on the promini directly?