!? The threat that has been there for quite some time. Whether this is actually a good move or not is another matter.. probably not. But an interesting one.

Had to, Kxf7 would've meant Nxe5 double check, and the bishop at g4 falls.

Necessary.

Builds the center. Offers a trap - exd4 cxd4 Qxe4 Re3, and the black queen falls.

Shifts the attack to the queen side of the board.

the pawns are the castle walls of the black king. Moving them should be done as last resort, especially as the bishop at f8 and the rook at h8 remain idle. exd4 could've been considered though as the black pawn there is solitary.

Refuses to give up the center, making it the white king's best defense. Also opens the bishop's line.

Better to bring the rest of the guns to bear. e.g. g5, Bg7, Rhf8 to contest the open f-file and to protect the e-pawn better. This one yields the f7 square.

tries to open the line of pawns defending the king

All of white's forces point at the black king. Black has a material advantage, but two major pieces remain idle.