Hi,
i hope i've understand well 
If you need to connect wireless your Android device with Arduino, the Mega ADK is not your board.
I mean: the Mega ADK works with an Android device directly connected using USB cable.
You can instead use (almost) any Arduino board, plus a Bluetooth module.
You can find BT module for about 5 usd, and you can connect this with Arduino using a serial (of better, sofwtareserial) connection.
This module is class 2, that means max 10 meters of range.
Class 1 is more expensive, but works in a range of 100 meters.
For Android programming, you can use also AppInventor:
http://appinventor.mit.edu/
that is a cloud & block programming platform (oss).