I think I have finally some ideas of how to make the mesh deform better. Since I am not that proficient in 3d stuff, there is much trial and error for me... Here is the model with the old mesh and run forwards, jump, die and idle animations (no textures yet): abby.zym
It was fun and I learned a lot, but I thought a rework from scratch would be best -- especially since I decided to start with a high poly model this time. First, it is easier if I only have to concentrate on the shape first, and in a second step worry about the topology/optimasation of the mesh (Blender has this very useful retopo tool). Second, the latest Blender version has enhanced texture/normal map/whatever-else baking tools. I haven't used them yet, but what I saw from screenshots looks very promising.
Here are some screenshots of the new model, still WIP:
001.png
002.png
003.png
As you can see, I am working at the ears right now.

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