This is a question you must answer on your own. But my thoughts are that either the smell of her blood was to taunting at the time, or for some reason the fact he is unable to read her mind. Still, no one, maybe not even Stephanie Meyer herself, may not know the true answer.
Edward.
It will be the same actors for edward and Bella
Edward, with an injection of his own venom, in a last desperate attempt to save her.
He sucked her blood.
SPOLIER ALERT!Edward is the one who changes Bella!
He was looking down her blouse.
Edward, he has to to save her life.
to change her
no, this is not possible.
YES
That he would change her into a vampire
to save Bella swan