On Bella's birthday.
Her birthday at the cullens was her 17th birthday.
it is striped, the colours are: -yellow -green (different shades) -white
It does not specifically say when in the book, but I'm not sure about the movie.
The book New Moon, it says that Emmett's last birthday was in 1935. I'm not sure exactly what day though.
California
I don't think it's mentioned, but in New Moon, when Edward and Bella are going to the Cullens' house for her birthday party, Edward says something along the lines of "the last birthday any of us had was Emmett in 1935"
well I'm not sure what you mean because in new moon the Cullen's leave because people will start to get suspicious of them not aging and jasper attacks Bella so Edward makes them leave because he doesn't want her hurt again. hope that helps. (: and no they don't celebrate birthdays because in new moon on page 23 Edward says the last birthday they celebrated was Emmett in 1935.
The Cullens leave i nthe beginning and don't come back till the end. New Moon is about the relationship she builds with Jacob.
She is 17 at first, 18 in new moon (and Eclipse) and then when vampire, they celebrate her 19th birthday (she hates it!)
yes
a very big part
philosophy