Auto-reboot would be nice because some folks don't read thoroughly and might not notice that they're
supposed to reboot. I had read this thread ahead of installing so I knew that it would take a while before knowing it would install, but I think a simple popup of sorts -or something to bring the user's attention to some information text- would be ideal (like the red text you already use), just to simply explain what's going to happen (eg installation will take about a minute and your device will reboot automatically).
It really doesn't need to be anything fancy, even aesthetically I wouldn't worry too much about it. Personally I think it's refreshing to have an app that
just works, it serves its purpose and you're done. It's a great app that really will only be used once, maybe twice if people choose/need to uninstall, so putting in lots of time to make it look pretty might be a waste of your valuable time.
