A. If you want to make the image smaller, edit the HTML were it says width, and make it a smaller size, 400 to 700 is usually perfect.
B. Unfortunatly, unless he actually knows were you live and threatens to personally and physically harm you, theres not much you can do except attempt to get a hold of the admin/mod of that forum and get him banned, which, upon his myspace threat, wouldn't do much.