Thanks Visvanath for the complete run down.
Derek, I remember having the same quetions as you in much earlier versions of Moodle (and their docs). The 1.9 MoodleDocs version has a better introduction and an overview section about the Cron Script which still applies to 2.x. This was not carried forward in 2.x versions of the documentations.
Today, I did a quick edit of the introduction of the 2.1 and 2.2 Cron pages. In the 2.x MoodleDocs schema it falls under "Installation". Since the page is not titled "Cron installation", it deserves some additional clues for the general user, IMO And as you point out , tried to give a better description of what it does, how it works in Moodle and how to trigger it without knowing how to program your website's cron server. All done with fewer words than this post, to keep the "Keep it simple" techno folks happy.
Good posts. Chris