An Eva Air Boeing 747-400, registration B-16406 performing flight BR-667 from Atlanta,GA to Anchorage,AK (USA) with 2 crew and hazardeous (flammable) goods on board, was climbing out of Atlanta's runway 09L when the crew reported a gear door problem and levelled off at 5000 feet. The crew subsequently reported they also had a hydraulic quantity low indication. After working the related checklists the crew climbed the aircraft to 9000 feet to dump fuel, requested runway 09L for the return due to performance necessities, the crew declared PAN advising they were still working on their nose gear issue, they had the gear down but weren't sure whether they had nose gear steering. On final approach the crew advised they had no nose gear steering and needed to be towed off the runway. The aircraft landed safely on runway 09L about 75 minutes after departure, the crew advised no further assistance was needed, and the aircraft was towed off the runway.