Link object rotation to its parent

I am reasonably new to programming in unity and I have been stuck with this issue for a couple of days now...

What I want is for an object that is instantiated on the press of a button then set to the child of the FPS Controller to always be facing the camera when you look around.

My current code is this (Its probably very messy):

 var objectOut = false;
 
 var prefabs : GameObject[];
 
 var maxDistance = 5;
 var minDistance = 1;
 
 var obj;
 
 function Update () {
      Screen.lockCursor = true;
     if(Input.GetKeyUp("1") || Input.GetKeyUp("2") || Input.GetKeyUp("3") || Input.GetKeyUp("4")){
         if(objectOut == false){
             objectOut = true;
             
             if(Input.GetKeyUp("1")){
                 obj = Instantiate (prefabs[0], Vector3(0, 0, 0), Quaternion.identity);
             }else if(Input.GetKeyUp("2")){
                 obj = Instantiate (prefabs[1], Vector3(0, 0, 0), Quaternion.identity);
             }else if(Input.GetKeyUp("3")){
                 obj = Instantiate (prefabs[2], Vector3(0, 0, 0), Quaternion.identity);
             }else if(Input.GetKeyUp("4")){
                 obj = Instantiate (prefabs[3], Vector3(0, 0, 0), Quaternion.identity);
             }
             
             obj.transform.collider.enabled = true;
             obj.layer = 2;
             obj.transform.parent = gameObject.transform;
             obj.transform.rotation = gameObject.transform.rotation;
             obj.renderer.material.color.a = 0.5;
             
             var Hit : RaycastHit;
             Physics.Raycast(Camera.main.ScreenPointToRay(Input.mousePosition), Hit);
             
             obj.transform.localPosition = Vector3(0,2,1);
         }else{
             Destroy(obj);
             objectOut = false;
         }
     }
     
     if(objectOut){
         if(Input.GetAxis("Fire1")){
             objectOut = false;
             obj.transform.parent = null;
             obj.layer = 0;
             obj.transform.collider.enabled = true;
         }else{
             
             var rcHit : RaycastHit;
             var theRay : Vector3 = obj.transform.TransformDirection(Vector3.down);
             
             if (Physics.Raycast(obj.transform.position, theRay, rcHit)){
                 var GroundDis = rcHit.distance;
                 obj.transform.rotation = Quaternion.FromToRotation(Vector3.up, rcHit.normal);
                 obj.transform.localPosition.y = (obj.transform.localPosition.y - GroundDis) + obj.collider.bounds.size.y / 2;
             }
             
             if(Physics.Raycast(Camera.main.ScreenPointToRay(Input.mousePosition), Hit, maxDistance)){
                 if(Hit.distance >= minDistance){
                     obj.transform.position.x = Hit.point.x;
                     obj.transform.position.z = Hit.point.z;
                 }else{
                     obj.transform.localPosition.z = minDistance;
                 }
             }else{
                 obj.transform.localPosition.z = maxDistance;
             }
         }    
     }
 }

When I add this:

 obj.transform.localRotation.w = 0;

which I would expect to work, it results in some weird rotation of the object and even the object sinking through the ground when I move it around on slopes...

Any help would be appreciated!