regarding whether or not to mat slightly beyond the edge of the image or not, Mark Citret was very adamant about showing the edges of the image so that one knew that the 'crop' in the frame was the photographer's choice rather than the framer's. at the AIPAD show in nyc this past february i was very careful to observe whether or not there was a prevailing approach to this. more images had mat windows that did not cover the edge of the image, but not by an overwhelming majority. additionally, among the images where the window began away from the edge of the image, not all were trimmed and dry mounted. some images were printed much smaller than the paper size, were not dry mounted, and must have been corner mounted under the overmat. my personal opinion was that the most elegant prints, on a presentation basis only, were drymounted with perhaps a half inch of bare mount between the image and the edge of the window.
btw, if you want to simply wallow in an ocean of photography created by artists who range from the emerging to the venerable, attend an AIPAD* show. it's immensely worth the time and trouble.
*for those in other lands, AIPAD is the Association of International Photography Art Dealers.