That's the intresting point, 'cause the books' main charackter is Elena. While Elena (Nina) was in the series, and Stefan is lived (like vampire) and before the ending this series was still Elena's storyline. But like this, its Stefan storyline.
Vampire Form, if they eat black or red grapes, they do not need blood. But they will vomit up any blood consumed during their vampire years- all of it. But after, a vampire can eat soft foods for a year. then eat normal foods.