The price tage are affixed automatically by the machinery that packages the books.
They have a price, and sometimes an item number, but not too often lately, they go by the SKU.
NO.
Not to all books. Dinesh deSousa's book was banned from Costco. When people threatened to quit their membership they backed down. They put the book back on the shelves but they refuse to put a price on it. Reason: items with no price don't sell. Their CEO is a liberal.