for the last one why cant black recapture with the queen?
Some puzzles from my tournament.

Much of what you say is true. Thus as white I would refrain from taking on d3, but instead just maintain that pin; if black goes ...Qe5 as you said, Qxc6 picks up a pawn, attacks the bishop on a6 without giving up anything, and although black is not immediately losing a piece, he's still not happy to be in that pin.
Of course, white was doing well from move one, but he managed to trade off his previously pinned c3 knight for the f6 bishop, which was in command of the long diagonal, probably making the technique easier.
I just had a really bad tournament, but I'd like to post some of these puzzles to get you an idea that you have to be watchful. Enjoy solving! (Note that these were only for my opponents.) Game 1 was last.
Game 2:
Game 3:
Game 4:
Game 5: