The 787 wings are built in Nagoya, Japan, and the fuselage in Grottaglie, Italy. The Dreamlifter was built to bring these assemblies to Seattle and Charleston for final assembly. Almost all Dreamlifter flights are long range across the Atlantic and North Pacific.
The airplane is very draggy and they really could use winglets to cut down on the fuel flow, but there were some airflow issues with the enlarged fuselage and it caused some unwanted vibration. That's why they took them off.