disqus_shortname tells Disqus which website account (called a forum on Disqus) this system belongs to.
disqus_identifier tells Disqus how to uniquely identify the current page.
disqus_url tells Disqus the location of the page for permalinking purposes.
There are many more configuration variables available, but these are the most important.
Shortname is already ok.
Identifier was set to 'post_' + post.key
Url was set to the full post path as recommended
Thread title was set to the same as the post title
Disqus setup
From install instructions:
Shortname is already ok. Identifier was set to
'post_' + post.keyUrl was set to the full post path as recommended Thread title was set to the same as the post titleFull vars doc
Tags separation
I never found out what the separator was until I got a bit deep in the code. Added text in post edit tags field to explain separation by line break.