There's something wrong with my line

I don't know where to start because the movie got me very confused. Hopefully it's all explained better in the book (courtesy of Stephen King), now it's just a mystery to me why there's people freaking out and turning zombies because of cell phones, who is the guy on the red hoodie, why John Cusack has become Nicolas Cage and what's up with the ending, is it a twist or an open interpretation?