Tournament Entry Rating is calculated by the formula (CurrentRating + HighestRating) / 2. The entry rating will never drop to more than 100 points below your Highest Rating.
Rated stats are updated within 24 hours of the last completed rated game.
Chaos theory is popularly referred to as the butterfly effect. It manifests itself as an exponential growth of error. Tiny differences in the starting state of the system can lead to enormous differences in the final state.