The prefetch is an option which you can opt-out from, and i think you are mixing prefetch and prerender, just to let you know Firefox has actually supported prefetching since...wait for it... 2003.
Surte, but one cannot underline enough the importance of relevant and correct examples. May I suggest something like "<a href='verybiglogoftheday/' download='log-2013-12-11.txt'>"
Yes, look at my example (http://jsbin.com/utugex/1/edit), the href is pointing to an .html file, so in the normal case the browser will display the content of the page but with the download attribute the browser will be forced to download it as "myfile.pdf".
Must the prefetch/render tags be present at first load, or might they be added dynamically with JavaScript? Pagination is a good example, since a news site might want to load the second page of an article only after the user get so far in. Single-page sites are another good use case.