I found a way to do everything with just one slider: display the current runtime, fast forward and rewind. Unfortunately, this is much more complicated with AI2 than with Kodular, because among other things the Slider component in AI2 has no TouchDown and TouchUp events.
So test this APK on your devices:
Since this question also arises frequently: You should also be able to pick and play mp3 files from the external (removable) SD card.