WMI Intrinsic Events consumption - how is it handled?

Question

I have recently written a C# application for monitoring a selection of server applications that restarts them in the event of a crash.

The application itself is working fine. However, I have a 'gap' in my knowledge that concerns me, and I have not found a resource that adequately fills in that gap.

Using my application as an example, I am polling a system class which reports intrinsic events, specifically __instancecreationevent and __instancedeletionevent using a ManagementEventWatcher and a WQL query.

Here's a partial (edited for the sake of brevity; removed error handling, UI update code, query string builder, restart timers, loggers, et cetera) example from the application:

private void Main_Load(object sender, EventArgs e)
{
    // _watchers[0] holds "__InstanceCreationEvent" watcher

    _watchers[1] = new ManagementEventWatcher(new WqlEventQuery("__InstanceDeletionEvent", new TimeSpan(0,0,5), "TargetInstance ISA 'Win32_Process' AND TargetInstance.Name = 'application.exe'"));
    _watchers[1].EventArrived += new EventArrivedEventHandler(Watcher_EventArrived);
    _watchers[1].Start();
}

private void Watcher_EventArrived(object sender, EventArrivedEventArgs e)
{
    ManagementBaseObject process = (ManagementBaseObject)e.NewEvent["TargetInstance"];
    String executablePath = process["ExecutablePath"].ToString();
    ApplicationInfo app = _monitoredApps.SingleOrDefault(app => app.Key.ToLower() == executablePath.ToLower()).Value;

    switch (e.newEvent.ClassPath.ClassName)
    {
        case "__InstanceCreationEvent": // process has started/been opened
        {
            // UI updates to show process id, session id and status
            break;
        }

        case "__InstanceDeletionEvent": // process has been terminated
        {
            Restart(app);
            break;
        }
    }
}

private void Restart(ApplicationInfo appInfo)
{
    // UI updates
    // Checks that the app isn't already running e.g. started by user before timer elapsed

    Process process = new Process();
    process.StartInfo.WorkingDirectory = appInfo.ExecutablePath;
    process.StartInfo.FileName = appInfo.ProgramName;
    process.Start(); // Elevated privileges not required
}    

I have two specific questions:

1. Are system classes that report intrinsic events (or system classes in general), reporting events only when they are subscribed to (e.g. by using a ManagementEventWatcher)?
2. If not, how and when are the intrinsic events being consumed since they do not appear to persist between polls?