Xubuntu does not have support for the Wacom settings panel in settings, but there is a workaround to get it on. Link: https://github.com/Zeioth/XFCE-Wacom-Settings
Next: you have four Express keys and a touch ring on your Bamboo. On my Intuos I have the keys as well but no ring. Perhaps the ring can be set up with that wacom panel, but I expect the keys w’not. I use my right keys for redo and undo and the left ones for zoom in and out. However that ring seems to do zooming so hopefully someone here has some advice for you.
Next I made setup scripts for my Intuos, a Bamboo1 and a Graphire 4. The Bamboo is only a pen, no keys, no ring, Pick up the scripts for the Intuos and Graphire here as examples: https://www.dropbox.com/s/6pe3gaidc09pnbb/mypaint-scripts.zip?dl=0
I am Dutch and so comments are in Dutch, but if really needed I can do English translations.
This page is most helpful too to get things setup: http://linuxwacom.sourceforge.net/wiki/index.php/Tablet_Configuration#Graphire4
Finding out the numbers for a key is not so easy. I ended up doing that by trial and error.
Finally, such a script is specific for an application. If you have it right for MyPaint it will need to be different in let us say Krita or Gimp. So i use the script to set up my Wacom and next start MyPaint. In Windows the setup panel allows for setups for different apps. But that is something way over my head. I would be fully lost in the workflow.
Hope this gets you going! MyPaint is great fun!