* How can I update the po files, formerly I used "make update-po"?

- You can call the build_i18n command with the -m (--merge-po) option:
 ./setup.py build_i18n -m


* The domain and further intltool settings from the setup.cfg are not
  applied correctly.

- Please make sure that there is no Makefile in your po directory.
  Intltool seems to prefer the values from there.