The kid story is true. He was jumping up and down (pretty vigorously) on the stirrups while the ride was running, and the horse couldn't handle the force of it and dropped out from under him. The kid was okay, but I sure hope his parents learned a lesson about making your children behave.
The first day it was closed, no horses were missing. I'm assuming that they're just taking this opportunity to give the horses some TLC; the carousel is nearly 100 years old, after all. And of course, they're probably checking them for stability, too. But like I said, the kid was pretty much stomping on the stirrups.
It's expected to be back open on Tuesday at the earliest.