With respect to CLocationManager docs....

Constant values you can use to specify the accuracy of a location.

extern const CLLocationAccuracy kCLLocationAccuracyBestForNavigation;
extern const CLLocationAccuracy kCLLocationAccuracyBest;
extern const CLLocationAccuracy kCLLocationAccuracyNearestTenMeters;
extern const CLLocationAccuracy kCLLocationAccuracyHundredMeters;
extern const CLLocationAccuracy kCLLocationAccuracyKilometer;
extern const CLLocationAccuracy kCLLocationAccuracyThreeKilometers;

Given that, I have the following questions.

1. What triangulation method (GPS, cell tower or wi-fi) corresponds to each accuracy level?
2. Does iPhone SDK utilize Skyhook Wireless API?
3. For kCLLocationAccuracyBestForNavigation, there is note stating the phone must be plugged in. Is this enforced or is it just warning the developer the battery is likely to drain quick from using the GPS receiver.

Thanks in advance.