Is there any way to overlay some lines and dimensions on the document so that one can see where the margins end and more easily examine the overall layout and ratios of elements on the page?
See for example, some of the illustrations of frameworks in this article on the canons of page construction and this one on margins (which displays dimensions).
\usepackage[showframe]{geometry}
would suffice. – Werner Jan 26 '12 at 7:06