:A picture is a file, so in the "toolbox" on the left side of the page, click on "Upload file".  The Upload page gives a brief review of licencing questions for pictures that you didn't make yourself.  It's easy if you made the image yourself; otherwise copyright can be sticky.  If licence is not a problem, pictures can be uploaded to Wikipedia:Commons and thus made easily available to many Wikipedia articles, projects, and outside users. 
 :Yes, the article currently does not use or define the terms "conventional" and "trackless" as applied to this industry, which I gather is a significant distinction.