ome of the extensions to install may have need dependencies as documented in the links below:
1/ Upgrade MediaWiki and its extensions ( [url removed, login to view]:Upgrading )
2/ Implement regular and automatic backups of the website ([url removed, login to view]:Backing_up_a_wiki). [We currently have backups of our storage space but not a specific backup of MediaWiki adadpted for restoring the wiki. Also we'll have to talk I guess about a place to store the backups - something we don't have for the moment.]
3/ Install the new search engine for MediaWiki, especially the Elasticsearch server ( [url removed, login to view]:CirrusSearch )
4/ Install the GettingStarted extension ( [url removed, login to view]:GettingStarted )
5/ Address the problem of performances - when loading a page, images are loaded from Commons ( [url removed, login to view] ) and take a big time to be loaded, especially when they are a lot images. Many solutions can be explored:  each time a page is created, load the image and store them in the website indefinitely  make the images stay in the cache forever (some indications about this are in [url removed, login to view]:$wgUseInstantCommons)  etc.