Alpine Connection Diagram Alpine CDA 7894RB Ipod Connection Question.?

Alpine CDA 7894RB ipod connection question.? - alpine connection diagram

I want to buy a used one for my friend.
As the main unit to find music on the iPod using the extra cable?
Is the music of the "form of removable media, such as computers and only reads the music from the hard drive of your iPod?
Then I am now in a position to a hard drive with the iPod and iPod adapter to work> USB> hard drive connectors to mount but without all the necessary cables stories.

Or will I just be better to have a broken iPod with a display or buy somehting like