CHIUDERE UN'APP (WINDOWS PHONE)

Application.Current.Exit();

NAVIGARE VERSO UN'ALTRA FINESTRA

this.Frame.Navigate(typeof(myPage));

PASSAGGIO DI PARAMETRI AD UN'ALTRA FINESTRA

// let's assume that you have a simple class:
public class PassedData
{
   public string Name { get; set; }
   public int Value { get; set; }
}

// then you navigate like this:
Frame.Navigate(typeof(Page1), new PassedData { Name = "my name", Value = 10 });

// and in target Page you retrive the information:
protected override void OnNavigatedTo(NavigationEventArgs e)
{
    PassedData data = e.Parameter as PassedData;
}