For what is the Special:TagsReport page good? I only know that there are some tags listed there. But not all tags are appearing that I used on that wiki. What does "special tag" mean? Are there special tags or what?
When I make a dot . on the end the name of my username (PhilippL), my user-tags won't appear in my PhilippL account. That means my user-tag will be added in user 'PhilippL.'! Why is there this dot information?
Ask on the forums. I don't know everything - in fact, there are more things I don't know than I do know. Alternatively, look through MediaWiki messages to see if one's got User Page or something in the name. I've seen it as well, and I'm fairly sure it doesn't require css.