Saving material, as the expired bishop situation no longer makes it advantageous for the pawns to be facing each other. Another option was fxe5. Except maybe that the queen would have to guard the square from the knight. Sort of binds things up. With this move, the queen is free to move.

This pins black's knight if it wishes to protect the pawn. The knight is pretty weak on a6. The king might proceed onto b5, attacking the knight, and there is no immediate way to save it for black without giving up the pawn.

Simply planning Qf1+ to see where white king goes. Carefully ensuring that there are no crazy pins possible first, as attempting to play the Queen Gambit following a Rook Gambit is typically ill-advised.

This attacks the e6 pawn, so the appropriate check is Qd5+.

Takes a pawn, protects the c5 pawn from being taken, and white can't Kxa6 because of Qxc3.

Does Qd4+ feel tempting for black?

No, because then Nxe6+ would have resulted in the Queen Gambit. This move protects that square, allowing black's queen the liberty to move onto other things in life. White no longer has a double-attack on c5, so that's safe.

Kb3 here would have been less fatal. Helpful is the new position of the black knight, which makes b4 unsafe, and the previously protected pawn on c5 which makes b4 and d4 unsafe. There wasn't a way to have known it, but saving that pawn was a good idea in retrospect.

Good game, white put up a very strong defense.