[xwiki-users] Beginner's struggle with configuration

I am very interested about putting my own xwiki but I've been messing with it and some problems came out. At first i thought it would be good to make subwiki's for "Programming", "Linux", "Mathematics". I could make template wiki and derive extensions and settings from it but how can I install additional extension to all of wiki's then? I have also modified my "Preview" page when I made my first article. I've clicked preview, saw typo, and clicked edit.. After some struggle with editing this article I've modified this preview page unwittingly. After some modifications I removed all previous revisions. What can I do in such cases besides reinstalling everything? I would like to solve such problems by myself in the future so if it's possible, please, give me workflow, not a single solution. I want also to have navigation for entire wiki with subwikis like: #Programming -> Language Scala -> Design patterns #Linux -> Settings -> Tools #Mathematics -> Linear algebra -> Calculus where ("#" -> wiki), ("->" -> space) I think I could make "Navbar" panel in global wiki and add "xwiki:Panels.Navbar" to all subwiki's. But now the work needed to add it everywhere is overwhelming. Is it possible to do it in config file? I do not like cms such as drupal for the problems with configuration by clicking. I could spend days to make everything ticking in my way. From the other way it's good for giving power to the users. Best wishes, for community and developers xwiki seems to be professional and awesome.