Can I link to an artist in­side a me­dia cred­it field?

You sure can. Just add the link at­tribute in the media-​credit short­code, found in HTML view for a post, or di­rect­ly when adding an im­age. For ex­am­ple, if your post contains:

[media-credit name="Artist" 
              align="alignleft" 
              width="300"]<img src="http://www.mysite.com/files/2010/09/image.jpg" width="300" height="450" class="size-300 wp-image-2" />[​/media-credit]

change it to:

[media-credit name="Artist" 
              link="http://www.artistwebsite.com" 
              align="alignleft" 
              width="300"]<img src="http://www.mysite.com/files/2010/09/image.jpg" width="300" height="450" class="size-300 wp-image-2" />[​/media-credit]

Note the link to http://www.artistwebsite.com above.