4. The answer is that you will see the same sights as when you are resting. That is because you and mirror are in rest one relative another. If your relative speed is 0, it doesn't matter how quickly you both travel in relation to other objects.
5. The relativistic effects will not alter if the speed of light is reduced to 50m/s. According to the principle of constancy (2nd postulate), the upper limit of speed is 50m/s, which will be impossible for material objects to achieve because as the speed of light decreases, the sizes of humans and all other materials decrease as well, decreasing our relativistic velocity and thus making c=50m/s unattainable for material objects, and thus the relativistic effects will remain unchanged. A pedestrian must use caution when crossing the roadway. Let's assume you see a car arriving at 60 kilometers per hour, or 16.666 meters per second, from a distance of 100 meters. It'll take 6 seconds to arrive, giving you plenty of time to cross the street. Because the light reflected from the car to your eyes left the car two seconds ago, the car will reach at your location in four seconds and hit you (if the car is travelling in the lane on the far side of the road). It looks to you that approaching automobiles traveling at the legal limit are traveling at a speed of 100 / 4 = 25 m/s, which is 50% faster than the genuine speed of 16.666 m/s. When considering whether or not it is safe to cross the road, one would quickly become accustomed to this.
6.
