> >!One thing, though. A major character for the good guys (Thorin) dies, as do Fili and Kili. That’s something kids might or might not handle well.!<

You should mark this with spoilers.

As for the death, A LOT of children's books, especially those written more than a few decades ago, have characters dying:

>!Charlotte’s Web, Bambi, a Life in the Woods, Harry Potter, Percy Jackson series, The Lion, the Witch, and the Wardrobe, The Giving Tree, Old Yeller, Bridge to Terabithia, Little Women, Esperanza Rising,...!<

And yeah, I bawled at some of them. Still remember.