You can use the column tags on other pages but then the articles will have 3 columns because of the right rail. You are not allowed to hide the right rail but you can use AddRailModule to add things to it.
Are you talking about a navbox or TOC? A TOC lists the sections on a page so it wouldn't be the same on all pages. If you are referring to a navbox, then you can just create it as a template.
Actually i meant a Navbox.
a) can I insert a navbox template railmodule
c) I found a collapsible navbox template on Fandom Template:Navbox_advanced I assume I don't need to import the one from english wikipedia;
but following question came up : this quote was on the documentation page "the CSS classes in MediaWiki:common.css and the collapsible table used to hide the box in MediaWiki:common.js."
so do I need to import these files from Mediawiki or are they linked when I import the template in my wiki
There is width restriction for level 1 but you can abbreviation names. Using your current TOC, an example of layout:
* Histoire de la Mini|Histoire
** Mini brand - la marque
** Sir Alec Issigonis
** British Motor Corporation
*** Morris Motors
** British Leyland BLMC
** Rover group
** Foreign License Holders
* Design - conceptions de la Mini|Design
* Modèles et variantes|Modèles
You should see if what TableWiz mentioned will work for your purposes. However, yes, you can add a navbox via AddRailModule. See the script's documentation for details.
Which wiki did you find the collapsing template on? If they are using custom CSS/JS, then it probably isn't using the standard feature. I would suggest you look into creating your own using the standard feature so that you don't have to deal with the JS.
For future reference, "Fandom" refers either to the company the runs the wiki farm or the farm as a whole. There are thousands of wikis each with their own templates. When asking how to use/copy a template, you should specify both the template and the wiki.
From what I can gather, you can copy the CSS if you want but it isn't critical to the main function of the template; it is just the default styling. As for the JS, it appears to be unused anyways so you should be fine not copying it. My guess is that the template used to use it but was later updated to use the standard Fandom collapse feature instead.