The engines, like the rest of the plane, is probably in a million pieces.
A plane does not drop into the ocean and stay intact, from 35,000 feet. Hitting the water would be like crashing into the ground. One engine could have flamed out before the other, and there would be an awful uncontrolled descent, probably end over end.
Fuel would have been in the wing tanks and very little would be seeping from anywhere. It would have been dispersed.
Who knows—this fuel could be seeping from an old wreck from years ago. The water is almost three miles deep in this area.
Not if it ditched at that point and the absence of debris in that area is a pretty good indication that the pilot set it down instead of crashing it especially since he had atleast 300+ more miles of fuel onboard.