Camera Scripting Help (Sims Style)

I am trying to make a game similar to the Sims games but my first step is making the camera to the game. So far I am able to pan the camera when I put my mouse to the edge of the screen. Right now the only thing I'm trying to do is:

-Be able to rotate the camera with the middle mouse button ie. look up and down or left and right -Be able to zoom in with the middle mouse scroll except I don't want to change the field of view but actually move the camera to where the mouse is pointed at when I scroll my mouse.

The only problem is that I don't know how and will very much appreciate to know where to start or references to help me with the camera.

Here's my script:

 var CamSpeed = 1.00;
 var GUIsize = 25;
 var distance : float = 120;
 var sensitivityDistance : float = 50;
 var damping : float = 5;
 var minFOV : float = 15;
 var maxFOV : float = 120;
 
 function Start () {
         distance = GetComponent.<Camera>().fieldOfView;
 
 }
 
 function Update () {
 
 var recdown = Rect (0, 0, Screen.width, GUIsize);
 var recup = Rect (0, Screen.height-GUIsize, Screen.width, GUIsize);
 var recleft = Rect (0, 0, GUIsize, Screen.height);
 var recright = Rect (Screen.width-GUIsize, 0, GUIsize, Screen.height);
 
 
     if (recdown.Contains(Input.mousePosition))
         transform.Translate(0, 0, -CamSpeed, Space.World);
     
     if (recup.Contains(Input.mousePosition))
         transform.Translate(0, 0, CamSpeed, Space.World);
         
     if (recleft.Contains(Input.mousePosition))
         transform.Translate(-CamSpeed, 0, 0, Space.World);
     
     if (recright.Contains(Input.mousePosition))
         transform.Translate(CamSpeed, 0, 0, Space.World);
 
     distance -= Input.GetAxis("Mouse ScrollWheel") * sensitivityDistance;
         distance = Mathf.Clamp(distance, minFOV, maxFOV);
         GetComponent.<Camera>().fieldOfView = Mathf.Lerp(GetComponent.<Camera>().fieldOfView, distance, Time.deltaTime * damping);
         
 
 }