The correct answers are: The getaway helicopter takes off at exactly midnight, so synchronize your watches. We will bypass the laser grid while the main guard is doing his rounds. I am meeting our buyer in Paris tomorrow morning to hand over the diamond.

Explanation:

• Present Simple for Schedules: "Takes off" is correct because the flight is treated as a fixed timetable.

• Present Continuous in Time Clauses: "Is doing" correctly emphasizes an ongoing future action after the time conjunction "while."

• Present Continuous for Arrangements: "Am meeting" correctly describes a fixed personal arrangement in the future.

Why the others are incorrect:

• You cannot use "will" in a future time clause starting with "as soon as." It should be "as soon as the security system deactivates."

• We do not use the present continuous for predictions based on present evidence. It should be "it is going to detonate!"