If the velocity of an object changes direction but its speed remains the same, it has or has not been accelerated.
The reason the moon does not fall into Earth is that the gravitational pull of the Earth on the moon is weak, the moon has a sufficiently large orbital speed, the gravitational pull of other planets keeps the moon up, the moon has less mass than Earth, or none of the above.
Ralph is confused about centripetal and centrifugal forces. When he is in a car which is turning to the right, he feels a force pushing him to the left. But the textbook says that the actual force is pushing him to the right. Can you explain this to him? What is he actually feeling during the turn? He is feeling the inertia of his body. When the car turns right, his body resists this change in velocity and tries to go straight ahead. In the reference frame of the car, this feels like his body is trying to go to the left.