I'm writing my first location based android app, but got confused about some of the GPS service api. Here are some questions I have:

1) To get my current location, I called requestLocationUpdates() with a listener in the onCreate() method of one activity. But what happens when another activity starts and the current activity goes invisible? Is the GPS location update going to stop? If so, how do I keep it on after the activity is switched?

2) how accurate is the Location.getSpeed()? How is it computed? Can it tell the difference between on bicycle and on foot?

3) not really a question about android. How to calculate the coordinates of a location, say, 100m away from my current location?

4) To stop the GPS, I only need to remove all the listeners that have been registered to locationmanager?

Thanks a lot!