Dear Sebastian,
If you have time and interest, would you kindly consider an alternative approach to this project's implementation:
- Use OpenStreetMap as the base layer for the map
- Add coffee places to OpenStreetMap for them to appear on the map
This approach might be a bit more complex than the current one. However, it is clearly aimed at geeks, and geeks are not easily scared of complexity :)
This website serves as a good starting point for OpenStreetMap:
http://www.switch2osm.com
Thank you.