Her control as a newborn is her luminosity, so far as I can determine - she has a set of generalized techniques to influence her desires and emotions, and takes advantage of the specific knowledge which she acquired from the others in her coven to focus these techniques on the precise alterations she needs to be a well-controlled newborn.
No, she had control in canon too. Luminous!Bella is only a touch more self-possessed. My explanation - maybe I haven't played it up enough? - is that if you know something about what to expect, you will do a better job of handling it. This is borne out by Carlisle being immune to wanting to nom humans, and having known vampires existed before he was bitten. The others have more trouble, and the one who has the most trouble is Jasper - who also was turned the most unexpectedly and traumatically, while the others at least expected to die of injury/sickness or had amnesia.
In the vein of the Harry Potter and the Methods of Rationality discussion threads this is the place to discuss anything relating to Alicorn's Twilight fanfic Luminosity. The fanfic is also archived on Alicorn's own website <strike>(warning: white text on black background)</strike>.
Previous discussion is hidden so deeply within the first Methods of Rationality thread that it's difficult to find even if you already know it exists.
Similar to how Eliezer's fanfic popularizes material from his sequences Alicorn is using the insights from her Luminosity sequence.
Spoilers for the fanfic itself as well as the original novels need and should not be hidden, but spoiler protection still applies for any other works of fiction, except for Harry Potter and the Methods of Rationality chapters more than a week old so we can freely discuss similarities and differences.
EDIT: Post-ginormous-spoiler discussion should go to the second thread. (If you have any doubt on whether you have reached the spoiler in question you have not.)