1- There appear little dots at the left side of the avatar comments, this was not the case before. What I can do for removing them?
The "little dots" might be standard HTML "List" item bullets, but that can only be a guess.
Mind that the information you provide is not sufficient to assist you with this kind of fully fledged customization.
When asking for assistance of any kind please generally post a link to your site and — where applicable — a page showing the subject of your question. A first hand look at the page could possibly tell us more about several aspects regarding current settings, which style you use, the markup in its context, as well as other details which are probably important when it comes to explanations, instructions or troubleshooting.
Without providing sufficient information you will rarely get a spot-on answer because everybody is left to guessing what might be wrong and how to approach your issue.
If you don't want to openly post the URL or it is set "Offline" (Joomla) or otherwise locked (via
.htpasswd for instance) just click Edit at the bottom right of your initial question (= the first post in this thread) and then use Add hidden information at the bottom left to provide the required access data.
Anything in the Hidden Information field will only be visible to the YOOtheme support team.
Once there is a page to inspect I will take a look to see what I can suggest.
2- The "area of operations" (item category) appears suddenly, but wasnt that all in all just a copy of the existing template I modified before? Why does this change wasnt assigned? I forget where I disabled the item category before. Can you tell me where exactly I can disable it, please?
Copying a template doesn't copy the elements and positions.
Thoroughly revise the configuration of your custom template's layouts (Full, Teaser, etc.).
Please take a look at the ZOO documentation in general and the chapter on how to Assign Elements to Layout Positions in particular.
there is no element in the sidebar...
Mind that the layout shown in your screenshot is completely empty. If it were really used for the frontend no content at all would be displayed. If you see content it is a clear hint that your are looking at the wrong ZOO template and the wrong layout.
How it comes that it does appear now?
Make sure you are looking at the very ZOO template and layout which is actually assigned to your app instance, not just any layout of any template.