Define force and necessitate the same?

a force is a influencewhich tends to set a stationary object in motion. or which tends to change the speed and/or direction of a moving object. or which tends to change the shape of an object.

No. Centripetal force is a real force that pulls objects towards the center of the circular motion. Centrifugal force is a ficticious force that seems to pull an object towards the outside.

yes because spring force is such an elastic force which acts in a spring.

Balanced forces mean the net force is zero, so they are not the same unless net force is zero.Net force is the vector sum of all forces on an object

No, it is equal in magnitude but opposite in direction.