What an adventure! The bit about passport control gave me a chuckle!
To answer your question about dumping fuel, airplanes are designed to take off at a much heavier weight than they land. Mainly due to the downward force the landing gear must handle on landing. For example, 777-300ER MTOW (Max TakeOff Weight) is 775,000lbs, while its MLW (Max Landing Weight) is 554,000lbs. That discrepancy is due to the fact that a full load of fuel for a 77W is ~48K US Gallons, at 6.8 lbs per gallon = roughly 325,000lbs.