The division director I worked for HATED getting handwritten essays -- he thought it looked sloppy and indicated that the applicant just didn't care. I can't say this is true for other adcomm members, but I don't think you'll go wrong by typing them.
As for the all-important staple/paperclip question, I prefer staples. Papers slip in and out of paperclipped documents easily -- you could end up with part of another application and they'll end up with yours. I do appreciate Paws' concern for the admin staff -- there is plenty of photocopying to be done -- but as a former administrator myself I prefer the certainty of the traditional staple.