Mega adk Car project idea's

I have a few Ideas for using my arduino mega ADK in my car but can't find information on how to do it.
Can you guys help?

1 How do I control my android phone's volume control from the mega?
2 If the phone rings, is is possible to send the call number to the arduino for it to display on another display? (and have the arduino control the volume?

Also can a digital pin read up to 6000 times a minit?