Loading/Unloading External File? + Fade Transition?

programming flash
1

On the stage I have a movieClip holder for my buttons (holderButton). The buttons are nested inside. For each of my buttons I plan to write the same code as below:

holderButton.btn1.onRelease = function() {
holder.loadMovie(“one.jpg”);
}

So btn1, btn2, btn3… which will load one.jpg, two.jpg, three.jpg …The jpegs will load into holder.

  1. Firstly, if I load an image in. Do I need to tell it to unload before the next one loads in?

  2. How do I make the jpeg fade in and out of the holder when loading? I need this to be actionscripted.