I'm having the exact same issues on a Mac.
Is there some file we can copy from the old version that will restore the "include a link" functionality, and fix the non-centered preview image?
The Link functionality is critical for delivering original images to clients (Link URL: ../hirez/{filename})
-Michael
Mac OSX 10.8.2, Photo Mechanic Version 5.0, build 13444 (c5a5ad3)