Maps vs. Overlays

[Heineken]

I find the map selection confusing, as there are actually only two map providers: MapsForge (not working for me right now, btw.) and Mapnik. The other options are overlays in the way I understand it.
Under "Overlays" I find 4 zeros (4 slots?) and no hint what they mean. (I assume I could use a recorded track here. Right?)
Suggestion:

1. Move all "maps" but the two actual maps to overlays.
2. Show a message when selecting an empty overlay slot.
   Or, even better, give an option to select a track.