I don't like the rook there, h4 seems better, eyeing on his king position.

26. Qxf6 and there is no defence against 27. Qg7 checkmate.

He did not, jkarp.

This is a blunder because it loses a piece and misses a mate in two. Better would be 28. Rf8+ Kh7 29. Qh8#

This is also a blunder because it allows white to mate in two again with the same moves as I stated above or starting with Qg7.

Qg7 doesn't work: ...Nxg7 and there's no mate.

One of two moves black could do.

Better would be Qxg7 because it gives you an immediate mate.