Why do we use radians instead of degrees as the unit of measurement in rotational kinematics?

This is because the terms used in rotational motion are analogous to the terms used in linear motion and can interchange each other with variation in the topic since their meaning is exactly the same. For example, what you call force in linear motion can be called torque in terms of rotational motion. Just replace the linear terms with angular terms and you are done with the major process.

This is the type of acceleration due to which a circular moment of the object is possible. This force constantly directs the motion of the body towards the centre of gravitation. Without this motion, the object will move away in a straight line. It ensures that the object stays in a circular path by changing the direction of object's velocity towards the centre.