I like to try Templater.
One question:
If I create some content

exemple: In Templater I create a table with some infos and images and want to insert this in existing articles (with already text, images, etc)
Are the complete article is replaced or the table in Templater is inserted in the existing article. (let say where the text cursor is in the article)???

The templates you choose are inserted in the text.

Cool, I try this right away. I was confused by your catch screen images that show all the possibility that concern a complete article.

What happen if you change these article configurations?

The settings that are available in the edit screen you are in will be overruled by what you set in the template.

So in the Administrator, when you edit/create an article, you can just about control all the settings.

In the frontend, only the options that you can see (or are in hidden form elements) will be set.

This also works for other non-article content items. But only if the dorm elements have the same names.