Filmmaker Guillermo del Toro has a lot on his plate — he’s spending the next few years in New Zealand directing “The Hobbit” — but he found time to co-author, with thriller writer Chuck Hogan, “The Strain,” a novel about a plague of vampires. Demons, monsters, and witches are a lifelong obsession for Del Toro. He tells Kurt, they were just part of growing up in Mexico.