Question regarding Spline Generated Path

[_Aka_]

1. I want to know How I Create a custom a custom CG Volume Controller so I can move objects along the path, with random deviation from the center of the spline considering these objects are rigidbodies that should detect collisions and deviate from their movement(I should be able to push them off the spline mesh) when collided.

You can do that without creating a custom volume controller. You can use a similar setup to the example scene 21_CGExtrusion, but instead of setting game over to true when touching an object, you can deactivate the volume controller, so it does not control the position of the object, and use your own code or physics to move the object. In the example the collider is a trigger, you probably want to set that to false.
If you still feel need to have a custom controller, take a look at this: https://forum.curvyeditor.com/thread-580-post-2030.html#pid2030