How to you connect to an Arduino with USB?
PocketBot to talk directly to the an Arduino using a OTG USB cable (http://www.amazon.com/
Does PocketBot tell my robot how to move?
PocketBot does not send movement commands directly to your robot. Instead it sends information about the world(sensor data) and you can decide what to do with that information in your Arduino sketch. For example it can tell you that a person is standing to the right. You have to decide if the robot turns towards the person or ignores them.