Pontious
I Hate to tell you, but you have shot yourself in both feet.
I would say most of the B757-200s flying in the USA have overwing exits. Delta, American, United and Continental to name the 4 big airlines. So thats the three biggest 757 operators in the world. So i would guess that there are more with overwing than without. You have been looking at aircraft operating in europe for to long.
So in all l think you owe Pointer a very deep Apology.
Deck-Cam
Yes you had better start with your reading.
Each pair of over wings has a slide, which comes out of a compartment just above the inboard flap.