Answer:

1.) in my own opinion an officiating official be phisical fit because referees get a lot of the same injuries and to prevent this,it is very important to do exercises that focus specially on strenght and stability .It prevents referees from getting injuries,but it also help them perfom better because they'll be able to move efficiently

2.)Measuring my target heart rate is considered as one of the safety precaution in doing physical activity because knowing your target heart rate help your pace you workouts.Exercising at the right level of intnsity will help you aviod burning out or wasting time with a workout thats not vigorous enough to help you meet your goals

3.)In my opinion the set of exercises should be done first is static exercises because the static stretching is done to increase your flexibility while your muscle is most prone to increase lenght.Then the dynamic warm-up should follow to prepare your muscle for exercises.Where as Blahnik recommends mainly using dynamic stretching over static stretching before the workout