2) One value might be distorted; for example it is usual that a heard rate right after sitting down can be higher than the rest rate. Other factors that might affect this is the rate of breathing, exercise. We also have that some bleeding can affect this. Finally, the point that you use to measure the heart rate can also be important in making correct measurements.
1)Taking multiple heart rates leads to more reliable results because you can use the mean and not a single value that might be far off it. You avoid thus the effects of the factors above that happen often enough so that we would appear to be ill many times when we are perfectly healthy; In scientific terms, there is some variance in measurements and that is fine.
3) Even if their resting heart rates are the same, they can react differently to stress. One reason is having low iron in your blood; it is essential for transferring oxygen in your blood and thus it is esssential when one does gymnastics. A person with low iron will have a higher pulse to accomodate his cells' needs for oxygen. The same applies to persons with breathing problems or different fitness (even if the resting heart rate is the same). Also, there could be the case that genetically one has less mitochondria and this also affects oxygen and blood needs in exercise.
4) The average rate for adults is 60-100 beats per minute. While this is not abnormal, it is rather high. An examination might be advised to see what leads to such a high bpm rate. If this yields nothing, it could be that due to age and physics reasons this is normal.
