thanks!
wrt 1 and 3: my bad, i had too high expectations for the default Docker image 🙂 , thought it was ready to run tensorflow out of the box, but apparently it isn't. I managed to run my rounds with another image.
wrt 2: yes, i already changed the package_manager to conda and added tensorflow-gpu as dependency, as i do in my local environment, but the environment that is created doesn't have access to the GPUs, as the other one does. How can i set the base python version for the newly created conda env?