Android :: Creating Sound Notifications But No UI

I am creating one notification based on some event. This notification will only create sound. I just want to generate the sound using this notification, but no UI. Following is my code for this:
// make notification sound whenever the device is connected or disconnected
Notification notification = new Notification();
notification.defaults |= Notification.DEFAULT_SOUND;
notification.flags = Notification.FLAG_AUTO_CANCEL;
NotificationManager manager = (NotificationManager)
mContext.getSystemService(Context.NOTIFICATION_SERVICE);
// notify to all, manager.notify(0, notification);

I am facing few problems and have some doubts. I tried to search for answers in this post but could not find, so I am posting here for your people's suggestions:
1. Here I am using 0 as id for the notification. Is it good in practice. Since, I don't want to that this notification conflicts with other.
2. I have one doubt, about notification ids, e.g. if i keep my notifications id as 1 and some other application also have set that as 1. In that case, will my notification be updated. or Android treats, application's notifications differently.
3. Is it necessary to add FLAG_AUTO_CANCEL flag in my notification. Because, I think this is used when notification will appear in the status bar. But in my case, I have no UI. It means nothing will appear in status bar.
4. Currently there is one problem. When my notification makes sound, sometimes it seems that it is suppressed or distorted by any other sound or event. I am not sure what is happening there.