Our wiki installation is mostly a vanilla MediaWiki
installation that hasn't been customized much at all, beyond a permissions system for hiding some areas (eg: Arm Game Developers).
Basically at the moment, it's mainly a very rough area where members can dump stuff in a way that's a bit more easy to organize than forum threads, and not like a regular wiki (very user friendly, nicely styled, consistent formatting, good organization and categories, a lot of readers who regularly tidy articles and contribute, etc).
We don't really have any bells and whistles beyond the very basic stuff that comes with a standard MediaWiki installation, because there hasn't really been demand for it (very few people actually edit the ARM wiki, in practice).
I think that those extra edit buttons (insert table, etc), are either customizations on each wiki, or are a feature that only newer versions of the software come with. I haven't spent time researching it yet, and didn't notice the missing button until now.
That said, it's pretty simple to add the wiki code for a table, even if there isn't a shortcut button for it:http://www.mediawiki.org/wiki/Help:Tables
And there's also a couple of examples of tables in our sandbox wiki page:wiki/index.php/Wiki_sandbox
But if you really want a button to click on, then I'll look into it. For instance there's this guide over here that I found for customizing the edit buttons:http://www.mediawiki.org/wiki/Manual:Cu ... it_buttons
And about the Infobox code you're struggling with, I think that's a more advanced feature known as Templates.
Again, not something that's built into mediawiki by default, but which needs to be added by users/wiki admins. There's more information about this process at these links:http://www.mediawiki.org/wiki/Help:Templateshttp://en.wikipedia.org/wiki/Template:Infobox
The second link also shows the code for the Infobox template, but actually Wikipedia has hundreds of other Templates.
As far as I can tell, the Template system doesn't do anything which regular wiki code can't do, it just saves a bit of typing, especially if you want to include the same type of stylized box or message on a lot of different pages.
Basically, it's a more advanced "Power User" feature for editors that do a huge amount of article editing, and want to keep a consistent style across the wiki.
But again, our wiki is barely used, and there's very little demand for this type of feature (which also looks kind of complicated to setup and to understand). Are you planning on doing a lot of wiki editing that would benefit from this feature?