Well, for your first question, it would be relatively easy to incapacitate the passangers and crew, especially if the pilots were involved.
Some of the crew may have been involved, too. Passengers may not have known they were hijacked until it was too late.
Relatively easy to incapacitate over 200 passengers??? How exactly? The only hijacking scenario i can think of is if one of the pilots does it by taking out the other with no one knowing. They’re flying in the middle of the night, and none of the passengers really know anything is wrong.