Is there an imaging software package which works best or is most compatible with Noteworthy?
Not from personal experience but other users' recommendations, I can say that Open Office handles NWC-originated metafiles well.
If by "imaging software" you mean that you want to scan printed sheet music, then look in the forum for comments by other users (use the search capability).
If by "imaging software" you mean that you want to make a bitmap (GIF, JPG) image of some music, that can be done. If you mean that you want to graphically post-process the notation, that can be done.