Would like information about how browsers render pages

I wasn't sure quite where to post this, but chose this forum as least likely to be the wrong place

Has anyone any good, moderately technical, links that explain:

#1 in what sequence the content of an html file is rendered by a browser (yeah, from top to bottom), and how multiple resources like external js, external css, images, text which all have different download times affect the rendering of the entire page.

#2 what differences exist between various versions of various browsers (well NS and IE anyway)