Glad to hear that you like the add-on!
The custom sound options isn't a feature that I looked into very much, but now that I know someone wants that feature, I'll see if it is possible to add this in an upcoming update. I'm not sure if it is possible with the current APIs, but I'll certainly look into it.
The ability to stop the sound after it starts to play is a good idea. I'll see about adding that feature as well.