She died in a car crash
Renee Dwyer, Bella's mom.
Sarah Clarke plays Bella's Mom. She is known from the TV series '24'.
Nothing really happens, shes still with Phil.
No Kyra Sedgwick was not in Twilight the movie although she looks like the actress that played Esme (Edward's mom). She's not and to make sure look up Twilight and click on the cast to see names.
Two flights of stairs, then out a window.