A bullet execution is the following (taking from the specs, bcd05):
"Each turn, a bullet moves from its previous point to its next point based on its direction and velocity. The ‘velocity’ is the distance the bullet moves each turn. If a collision is detected along this line, the first object it collides with is dealt damage, and the bullet disappears. If it collides with the wall of the map, the bullet disappears."
@komodo009 this means collisions are detected along a line segment between the bullet's start and end points during the bullet's turn.
@aliamir I just posted a reply to a question here that describes a situation with this execution order. For your second question, the status of the robot that fired the bullet does not matter. The bullet remains in the execution order regardless of whether the robot that fired it is alive or dead.
@kodin The bullet is placed 0.05 outside the circumference of the shooting robot, and may overlap with another robot. Currently, the other robot will see this bullet and have a chance to move before the bullet propagates and processes collision.