re: InDash android tablet as car headunit

Like I said, I reused the factory headunit, just hid it behind the dashboard essentially. I have an App for the tablet that talks to the cars computer to control volume, etc. Can even send the tablet a text to remote start the truck.

As far as wake/sleep, there is an app called tasker that will do certain actions for set events. I set it up to unlock when power is connected to the charger, and to go to sleep when power is disconnected.

Haven't tried those FM dongles, but I would assume they would work out fine. If thats the case, I would just come off the headphone jack of the tablet straight to an amplifier to the speakers. Eliminate a headunit all together