Just in time to see Amy throw up her hands and go down

Hello everybody.

In the following I copied a part of a novel.

behind, striking out toward the smoother ice in the middle of the river. For a minute Jo stood still with a strange feeling in her heart, then she resolved to go on, but something held and turned her round, just in time to see Amy throw up her hands and go down, with a sudden crash of rotten ice, the splash of water,and a cry that made Jo's heart stand still with fear. She tried to call Laurie, but
her voice was gone. She tried to rush forward, but her feet seemed to have no strength in them, and for a second, she could only stand motionless, staring with a terror-stricken face at the little blue hood above the black water.
Something rushed swiftly by her, and Laurie's voice cried out...
"Bring a rail. Quick, quick!"
How she did it, she never knew, but for the next few minutes she worked as if possessed, blindly obeying Laurie, who was quite self-possessed, and lying flat, held Amy up by his arm and hockey stick till Jo dragged a rail from the fence, and together they got the child out, more frightened than hurt.
"Now then, we must walk her home as fast as we can. Pile our things on her, while I get off these confounded skates," cried Laurie, wrapping his coat round Amy, and tugging away at the straps which never seemed so intricate before.Shivering, dripping, and crying, they got Amy home, and after an exciting time of it, she fell asleep, rolled in blankets before a hot fire. During the bustle Jo had scarcely spoken but flown about, looking pale and wild, with her things half off, her dress torn, and her hands cut and bruised by ice and rails and refractory buckles.

Now would you please tell me what 'throw up her hands' means? Does it mean Amy stop struggling?

What does things in ' Pile our things on her', mean? And also in ' looking pale and wild, with her things half off,' I can't understand half off. I gusee things mean clothes and off mean hanging, am I right?

And do ' buckles' refer to the straps of skating shoes?

Thanks so myy for the help ??.