display. Today, GeoHack or WikiMiniAtlas don't do any of that. Is there a established procedure for adding new type values?
WikiMiniAtlas changes the appearance of the marker icon based on the type. Consensus is that new types should not be added, as we do not want to replicate the category system of Wikipedia. Custom marker icons are not accounted for either. For the WikiMiniAtlas it would be relatively easy to parse the categories of an article and choose marker icons accordingly.
For villages/towns/cities, it is a custom to add type:city(9876) with the population in parenthesis. But is this supported by GeoHack or WikiMiniAtlas? Does the presentation scale (zoom
The size of the dot marker on the WikiMiniAtlas is chosen according to the population number. Furthermore the display priority of the label depends on the population number (as well as the article text size) to ensure that big cities get displayed at small zoomlevels to facilitate easy orientation on the map.
out. Do we need to specify scale for each place, in addition to type (and population)?
The types imply default scales. This is implemented in the WMA (although not for every type if I recall correctly).
Of the 183,000 coordinates in the German Wikipedia, some 76,000 specify the physical dimension, the diameter in metres, using the parameter "dim", for example type:city_dim:25000. It seems that this value is often one tenth of the scale parameter. Is this supported by GeoHack or WikiMiniAtlas? Is it planned to be supported in the future, or is it an old feature going away?
Dim and scale are both supported by the WikiMiniAtlas. Scale is deprecated at least on the german WP, as it is meaningless without knowing the output resolution of the display device (the WMA uses 70dpi which used to be a standard monitor resolution and at least gives you the right ballpark)
It is common that the coordinate template for creating the GeoHack link is called indirectly from an infobox template. In that case, the infobox template takes parameters such as lat_deg, lat_min,... In the Swedish Wikipedia, we have tended to go away from that and instead call the coordinate template directly from each article. Is one way better than the other? Is there a global trend?
That is somewhat a matter of taste. There was a consensus(?) on en WP to use the coordinate templates in the infoboxes, but there are arguments for having coord parameters in the infoboxes (the infoboxes then can set sensible default values for coordinate parameters such as type and population (which would have to be specified redundantly otherwise))
How will the introduction, presumably later this year, of inline maps from OpenStreetMap, effect the questions above?
I will be out of a job :-)