Classes versus Action Script files.

This is a multi-part question...

1st- What is the difference between an .AS file that contains a class and one that dosen't...

2nd - Can the value of a variable be transfered between the two files... (by the way I'm refering to the 'deconstructing the video gallery" available on Macromedia's website.)

3rd- Instead of having all the video show in a window, I'm trying to create a scroll, so that I can just show 9, and when we click on a the scroll arrow, the clips move to reveal the others ones....

Any idea on how I should do that... is it in the shell.as, the thumb.as ???? I know what the logic should be, but when I try to get an index value from an .AS file, I get an error.

thanks

markyyy