Cordova long running location service

Question

I'm confused about when an app goes in the background and what the implications are when an app goes in the background.

I'm trying to have a long running service that detects location changes.

Plugin.xml:

<service android:name="MyLocationService.java" />

MyLocationService.java

public MyLocationService extends Service implements LocationListener {

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        //arguments for requestUpdates defined elsewhere
        this.locationManager.requestUpdates(minTimeBetweenUpdates, minDistanceBetweenUpdates, myCriteria, this, null);
    }

    public void onLocationChanged(Location location) {
        if (/*rare condition*/) {
            PluginResult result = new PluginResult(PluginResult.Status.OK, "We made it!");
            result.setKeepCallback(true);
            MyPlugin.callbackContext.sendPluginResult(result);
        }
    }
}

MyPlugin.java

public class MyPlugin extends CordovaPlugin {

    public static CallbackContext callbackContext;

    public boolean execute(String action, JSONArray data, CallbackContext callbackContext) {
        Activity activity = this.cordova.getActivity();
        Intent myIntent = new Intent(activity, MyLocationService);
        MyPlugin.callbackContext = callbackContext;
        activity.startService(myIntent);
    }
}

My questions are:

1. When will the onLocationChanged stop receiving updates?
   I know it'll stop receiving updates when I call locationManager.removeUpdates, but I wonder what other conditions will cause it to stop receiving updates...maybe when the app goes into the background?
2. When will I not be able to invoke the javascript callback via Cordova?
3. Are there better ways to have a long running service that will "wake up the app" when necessary?