How are you getting the audio from the android/cameras back into the EPS? Just using the Aux In port?
Reading this thread gave me the idea to create my own version using a Raspberry Pi as the carPC. The RPi already has a DC input for power (standard mini-usb cellphone charger) -- which means an inline battery like yours should be no problem to keep it running for days without drawing the car battery. I have many ideas such as:
Powered USB Hub (like the one you mentioned)
Storage via USB Hard Disk, 1TB
DVR for CCTV Front/Rear
USB WiFi Adapter - Tether to Jailbroken iPhone for mobile web, but also to connect to the infrastructure APs at both my home and office for automated downloading of local content such as DVD rips, TV shows, Music, etc...As well as automated upload/deletion of CCTV video data to storage servers in my company's cloud when the proper SSID connection is detected (I'm also a programmer, so some of this would require custom code of course).
I'm still working out how I'd control the screen, I see you guys have kicked around a couple of ideas including touchpads and remote mice. I wonder if there is any way to catch the input from the CIC iDrive controller itself in Linux? Maybe RS-232 to CAN or something along those lines, but I confess I know little about it currently, will need to do more research.
My other concern is the quality of video/audio with the Chinese MMI's that everyone is selling -- the Modmynav/Alekshop/etc.. kits are really all the same MMI part, and from what I've seen it looks to be the only one available. "Luckily" I suppose, the RPi has a RCA Video out port along with its HDMI port, so it can connect directly to the MMI along with a 3.5-to-RCA cable for the audio. The audio is another area where I'm not exactly sure what the best route to go is, suggestions welcome -- but if the standard solution is AUX IN i'm a little concerned because I've read that the quality can be quite low on that input.
Overall, great thread, very cool install -- Thanks for the inspiration as well!