This solved my problems. Thanks for hint, Christhiana and Drongle McMahon.
Simple explanation for newbies like me:
1. Paint the texture in Blender as you do normally
2. In UV-view save image (png for example)
3. Do the model export+import as dae normally. Forget textures. Only care about physics.
4. Upload the image separately (and pay 10L :-)
5. Apply the texture. It will be automatically aligned as it was in Blended. Magic!!