How to make a sprite retract to its original position?

I'm currently trying to implement a Yoshi's tongue, where it "whips" to a coordinate, and return back to it's original position. So far, I have gotten the tongue to leave the mouth, and travel vertically, but what could I add to it so I could achieve:

1. A max translation, (cannot moveTo further than this y-coordinate)

2. After an interval of ~0.5 seconds, the sprite retracts to it's original coordinate

3. Pushing the key down will not do anything while the tongue is at the maxTranslation, or while it is in motion

So far I have this code to make the tongue go out:

 #pragma strict
 
 function Start () {
     transform.position.z = -0.5;
 }
 
 function Update () {
     if(Input.GetKeyDown ("space"))
     {
         moveTo(transform.position.y + 10, 50); // Feed the moveTo() function the X/Y positions you want to move it to, and the Speed you want to move at
     }
     transform.position.z = -0.5;
 }
 
 function moveTo(posY : float, speed : float)
 {
     while (transform.position.y != posY)
     {
         transform.position = Vector2.MoveTowards (transform.position, new Vector2(transform.position.x, posY), speed * Time.deltaTime);
         yield;
     }
 }

Thanks, any help is appreciated.