XML Gallery: preload on current image/cross-fade image

I am new to action script but I am learning quickly.

I took the following tutorials and made a hybrid:
[/color][font=Verdana][size=4][color=Black]Photo Gallery Using XML and Flash[/color][/size][/font]
[font=Verdana][size=4][color=Black]Photo Slideshow Using XML and Flash[/color][/size][/font]

I redesigned the interface and created this:

Everything works great, but now I want to take it further than the tutorial.
I am trying to make the images cross-fade. I am open to any suggestions and I have tried many techniques with little success.

Here is the closest solution steps I have come up with:

1) First image preloads (grey background showing)
2) First image loaded into top level MC 1
3) First image fades in
4) First image in top level MC 1 remains visible
5) First image gets loaded into bottom level MC 2 behind current movie clip. 
6) Top level MC 1 clears because its preloading next image
Bottom level MC 2 remains visible
7)   Preloader shows on top of bottom level MC 2
8) Next image is loaded into top level MC 1
9) Next image fades in (cross-fade effect achieved because previous image is behind it)
10) Next image gets loaded into bottom level MC 2
Repeat process

I can’t get the action script to do what I want. I have off set the moveclips to show that the images are loading into both movieclips. I currently have the ‘nextImage()’ function controlling this so it is understandable the both images are cleared because the function is loading new images into the movie clips at the same time. How do I get one movie clip to remain constant while the other is loading? It seems to be a matter of where the function is placed. Or so I think.

I would appreciate any help I can get on this. If would also appreciate any suggestions for making the code for the control buttons cleaner.

Thank you,