Originally Posted by
Rainboe
They had a sudden, violent and totally unexpected wake encounter at an early stage.
The pilots were expecting a significant wake encounter, and were cautioned to expect it by the tower - it could be argued that by the tone of voice on the CVR, the handling pilot wasn't too happy about how soon they were departing after the JAL 747. The rest of your points are bang on the money from this laymans point of view.