Hi!
Thanks for the clarification. I turned the language temporary to english (because I didn’t want to mess up anything 😉 ) and disabled caching temporary for testing.
1. Okay, now it shows related posts from the same categories (some posts have more than 1) where the post is in. I’ve made a few modifications on the plugin code to achieve that.
2. It’s actually adjustable on the backend, but I did it for you: http://i.imgur.com/oODM4sZ.png
The plugin should work now as you expected.