Is there a recommended font and size for a job application?
It really doesn't matter what font you choose, as long as it's not unprofessional.  You can safely choose any font you might use for a research paper, 10 to 12 points in size (preferably 11 or 12, for the benefit of those with poor eyesight, but 10 is OK).  It's not worth worrying about this too much.  You can't help your chances through elegant typography, and the only way you can hurt them is if you do something ridiculous.  Any effects on readability are probably small, and I don't think most hiring committee members have strong opinions on the matter (while the ones who do don't always agree).