Apple like camera Panning(Finding mouse speed and apply it to camera)

Does any body know how to make a smooth pan based on the speed of the mouse. its for an overhead type strategy game. i have been trying to work on it for a while heres my code so far (p.s. its a bit messy):

// Dont have to read its just a reference

 var startingMousePosition : Vector3;
 var x;
 var y;
 var usingGUI : GuiStart;
 var xSpeed;
 var ySpeed;
 var xZero;
 var yZero;
 function Update () {
 
 var time = Time.fixedTime;
 usingGUI = GetComponent(GuiStart);    
     if(usingGUI.isGui == false){
         Debug.Log(usingGUI.isGui);
         
         if(Input.GetMouseButtonDown(0)){
         x = transform.position.x;
         y = transform.position.z;
 
         }
         
         if(Input.GetMouseButton(0)){
             xZero = Input.mousePosition.x;
             yZero = Input.mousePosition.y;
             xSpeed = (xZero/time)* .1;
             ySpeed = (yZero/time)* .1;
         
             x -= Input.GetAxis("Mouse X")*.1;
             y -= Input.GetAxis("Mouse Y")*.1;
         
             transform.position.x = x;//+xSpeed;
             transform.position.z = y;//+ySpeed;
         //Debug.Log(x + " " + y);
         }
     Debug.Log("This is x's Speed: " + xSpeed);
     Debug.Log("This is y's Speed: " + ySpeed);
     //Debug.Log(time);
 //Debug.Log(x + "and Y: " +y);
 
 }
 }

but here is what i want it to do, i want it to find the starting point of the camer( to zero it out) and then add the mouses speed to the cameras tranform, but i dont know how to find the mouses speed at all. and then if i could find the mouses speed how would i stop the camera after a bit?