YES, Hiccup's voice was awful. Maybe even worse than the adult Vikings having Scottish accents.
As far as the book goes, in the book the dragons are smaller, and every Viking child must capture and train one to use for hunting. They are NOT enemies. Hiccup ends up with a dragon that is tiny and has no teeth, hence the name Toothless. This dragon is of the most common variety, too. Of course, there's a lot more than that going on, but that is one huge difference between the book and the movie.
The book has a totally different, and in my opinion, much better plot than the movie.