Boss fight solution: he flies either on the top or the bottom of the room. Wherever he flies with his mouth closed is where he will NOT fly with his mouth open. So, if you see him with his mouth closed at the top, stay there. When his mouth is closed he doesn't take your fairies.
I almost never make it into windows. I never see that it's a building with a window until after I jump and smack into the wall above it. Those windows take too much precise timing. Still a great game; I love the music and background.
Sir, they have an endless stream of deadly arrows.
Send wave after wave of our own men at them! Tell them to walk leisurely, at a snails pace. How could we fail?