So i finaly got my sprites to work correctly. They actualy look better then i thought, but i will still have to use grass models for the borders between grassy and non-grassy areas.
I also started to work on the layout of the map. Got everything sketched on paper and build some first areas in the editor. Subdividing huge areas of your map is no fun and takes forever, so i spend the last weekend blocking out the main terrain geometry and fixing it all for subdivision ... lots of trial and error .... lots of waiting ... and lots of frustration