increasing speed and time of spawn game object

Good morning to all, I have ventured a short time ago in the world unity and of the scripting. In the creation of my mobile game I have found a problem. I would want my game object to have a spawn and greater speed increasing in the time on the axis of z. The script that I use to make moving the game object is this:

 #pragma strict
 
 var target : Transform ;
 var moveSpeed = 3 ;
 var rotSpeed = 3 ;
 
 var myTransform : Transform ;
 
 function awake ()
 {
   myTransform = transform ;
   
  }
   
 function Start () {
 target = GameObject.FindWithTag("Player").transform;
 
 
 }
 
 function Update () {
 myTransform.rotation = Quaternion.Slerp (myTransform.rotation, Quaternion.LookRotation (target.position - myTransform.position),rotSpeed * Time.deltaTime);
 myTransform.position += myTransform.forward * moveSpeed * Time.deltaTime ; 
 }
 

While what I use to do spawn them is this:

 var hazard : GameObject;
 var spawnValues : Vector3;
 var hazardCount : int;
 var spawnWait : float;
 var startWait : float;
 var waveWait : float;
 
 function Start () {
     SpawnWaves ();
 }
 
 function SpawnWaves () {
     yield WaitForSeconds (startWait);
     while (true)
     {
         for ( var i : int= 0; i < hazardCount; i++)
         {
              var spawnPosition : Vector3= new Vector3 (Random.Range (-spawnValues.x, spawnValues.x), spawnValues.y, spawnValues.z);
              var spawnRotation : Quaternion= Quaternion.identity;
             Instantiate (hazard, spawnPosition, spawnRotation);
             yield WaitForSeconds (spawnWait);
         }
         yield WaitForSeconds (waveWait);
         }
     }
 

How do you advise me of proceeding?

Ps Sorry for my bad english.