When your opponent chains "Book of Moon" to your "Huge Revolution" and flips 1 of the 3 monsters face-down, "Huge Revolution" has already been activated correctly so the effect of "Huge Revolution" resolves.
When your opponent chains "Ring of Destruction" to your "Huge Revolution" and destroys 1 of the 3 monsters, "Huge Revolution" has already been activated correctly so the effect of "Huge Revolution" resolves.
"Huge Revolution" destroys both face-up and face-down cards.
If your opponent activates "Huge Revolution" and you have "Pandemonium Watchbear" and "Pandemonium", your "Pandemonium" card is not destroyed.