As far as duplicate content goes read this
http://www.liztomey.com/my-last-stan...icate-content/
Theres a specific type of duplicate content she thinks is bad but it may be just her opinion. I think if duplicate content was a problem with Google then Associated Press would be out of business...
I do agree with Theresa...your resource box is your gun and the links are ammunition. When I submit articles I link to my site off of a keyword AND put in the URL. I've used PLR content and all I did was rewrite the headline, intro, and last paragraph with my keywords in mind. Cut out some stuff i didn't like and added some stuff I thought was missing...again with keywords in mind. This will change the PLR by about 30-60%, making it unique. You could rewrite more of it but if your going to do that you might as well write a unique article
I don't submit PLRs to article directories...I only them sparingly or if I'm out of steam and want to post something.
--Mike