I have a field on the Opportunity products that I want to display in a field on a document. Is this possible?
Yes this is possible. When you create your DDP, open your document and be sure to reference the field you want as the tag you place within your DDP. That way when you document package runs, it will replace the tag with the field you setup as a tag.
Check out this video on tagging a document Tagging in Word - YouTube