Hi!
We're looking into documenting this better but I was also not able to
make it work "out of the box". There is a ticket very closely related
to this:
https://phabricator.wikimedia.org/T205922
Another place to find other people who might have similar problems is
the fairly new Wikibase Users' Group Mailing list which you can find
at:
https://lists.wikimedia.org/mailman/listinfo/wikibaseug
You might find also it useful to take a look at:
https://www.mediawiki.org/wiki/Manual:Sites_table#Adding_a_new_site.
From the way you describe it your second problem is
most likely
related to the first one.
Best,
Tom