The aircraft is big, but the increase in size over the B747 isn't that great - except in its wingspan. Once you get to that sort of size, small changes in fuselage diametres and the like produce big changes in volume - and weight. The A380 is considerably shorter than the A340-600, however.
The 11:00 departure time, like all airline departure times, is from the gate. It is not a takeoff time. Similarly, the arrival scheduled time is at the gate, not the time of landing. 25 minutes from departure to takeoff is about right.