A1. When you are navigating towards a destination, you will see a blue arrow on top of the compass face which points straight towards your destination (not to be confused with the direction towards your next maneuver).
A2. When run on an iPhone 4 or 3GS, the compass can be configured to display your direction using the built in magnetometer (digital compass) or to provide a heading using orderly changes in position from GPS location data. Press the center of the compass to toggle between the magnetic compass, the GPS satellite-based compass, and the third option which automatically selects between the two modes for you based on your current speed.
A3. The magnetometer in the iPhone 4 or 3GS is susceptible to magnetic interference from electronics and ferrous metals. If an accurate direction cannot be achieved due to interference, you will be instructed to move away from the interference and re-calibrate the iPhone 4 or 3GS by moving it in a figure 8 pattern.
A4. Yes, you should see an option for MotionX-2D Direction-Up in the maps menu, which uses the heading provided by the magnetic compass in the iPhone 4 or 3GS devices. Press the calipers icon in the lower right area of the map to see your various map display choices.
A5. If you have a Simulate Trip Automatically animation running, the compass will reflect the heading of the location arrow as shown in the simulation. The Compass will revert to normal when the simulation stops.
A6. Speaker magnets and the alternator in your car can cause interference with the compass built into the iPhone 4 or 3GS. If this occurs, a popup will display asking you to move the iPhone away from the interference and re-calibrate by moving in a figure 8 pattern. Since this is unsafe while driving, you can simply tap on the popup and the map will switch from Direction Up to Course Up.