Hi Marko!
Where are you getting the "Fix my address", and which info file would you like to augment? The default mkgmap style does translate shop=organic, but the menu entry is called something else. Some day I should document it better, at http://www.polkupyoraily.net/osm/ or at a more appropriate place.
I click on a POI that eg has no special icon, just a small square, in my Garmin: Then I get the choice: name, in this example Fresh house, then the area below, if tagged and the area below this area. I think it could be helpful to know that is a store that sells organic food. (i.e. just to write the tags into this field) There exist many tags that are not mapped to special icons in Garmin devices. This is also a bit complicated since there are so many. So it would be really helpful to be able to read them. (That is also something that I really miss in Potlatch: If I see a green point, I have to choose edit just to see its features). Since I am not a very experienced mapper I always have the fear to damage something. Dani