1.This unit has built-in amp. If your car has optic fiber, then please connect this unit's sound output to your original car's speakers.
2. Yes, the speed is quick, you can see the video.
3. No, android 4.0 is the newest version. And users can't update this unit by themselves.
4.If your car has no optic fiber, then just plug and play.
If your car has optic fiber, then the installation will be a little complex. If you have any questions about installation, please send us the photo of your original car's plugs, then we can make a wiring diagram for your car.
http://www.seicane.com/android-mercedes-benz-c-class-w203-head-unit-stereo-upgrade-replacement-installation-user-manual/#tab2
By
Seicane