Ok, this is my first time posting so bear with me if i sound like a noob

I have a 2007 audi a8 (d3 facelift, mmi 2g) and I've been going back and forth between putting my iphone or a car pc on my oem mmi screen
Either way I'm hoping that through the canbus I'll be able to use the factory mmi/steering wheel buttons to control it

My plan is to use the below video interface module, my iphone 4s, an iphone a/v cable, and a couple jailbreak apps to get my iphone on the oem screen (similar to the mimics x2)

Here is where it gets tricky, the a8 has a motorized screen that comes out of the dash, so unlike the mimics interface, I do not want to make it a touchscreen for fear of breaking it from touching it

instead I would like to
a.) hack the can bus to talk to the iphone as a serial device (like when using a mouse to control the iphone via the btc mouse/keyboard hacks)
I would want to only program a few key buttons (siri, home, volume, phone, next/previous track, play/paue, safari, a couple random car useful apps, etc..)
The plan would be to use siri or the physical iphone for any text input.

b.) use the mimics solution but mount the touchscreen film on the cupholder instead of on the screen and calibrate it to work like a wacom tablet or a touchpad). The hope is with this solution that the touchpad would seem somewhat invisible and oem

c.) if i can't figure that out I would probably just mount a touchpad in the cupholder or just wait for leapmotion and use that to control the iphone (video input would be the same)

My questions are:

Does anyone know what I would need or if its even possible to send commands to the iphone via the oem mmi/steering wheel buttons? I've looked at the canusb interfaces, and some other interesting stuff (mimics, a centrafuse installation using the oem mmi buttons to control it). I'm a system administrator by trade, so i can get pretty technical, my programming/development skills have never been strong though

If not is this easier accomplished through android?

If I used a pc, what would i need to get the mmi controlling the pc? Any recommended accessories to make a pc setup be more audi friendly? (I'm open to a pc solution, i can connect it to the internet easily via 4g. I just like the idea of using the phone because i like having one consistent interface. my phone goes everywhere, if i update the music, contacts or apps i want that to reflect to my car solution)

One last question i have is what would it take to get custom text displayed on the instrument cluster (sent via the phone or a pc)

thanks in advance for any help pointing me in the right direction
I'm in the chicagoland area if anyone has any interest on working this. I figure this is a beta, if it works i would want to control more of the cars components (climate, lighting, etc) from the iphone or pc through some sort of can or vagcom interface