I've always been curious what the negotiation is because obviously there's certain movies that every film wants a trailer on, like Star Wars, and I don't know how Disney makes the decisions as to what it does and doesn't put on there. I'm assuming that whatever movies are the same studio as the film get first priority, but then everybody else is fighting for the remaining spots.
The process of creation goes on all the time. When I get through, I feel I know what the character will do in every situation. But the building up of the part is not mechanical or deliberate. It grows out of the text.