What are you using the alpha effects for? For transitions? It depends on how your site is setup and what you’re using it for. You’re not giving us much detail so I can’t really tell you where it should go.
well i guess it’s a transition… but only when the site loads in the beginning… my site has one screen for picture and one for contents… and i divided them into folders… and each folder contains layers of bg, content, border,etc…
i tried to divide them as specifically as i can…
For your first question, if you’re planning on applying it when the site loads then it should be part of your main movie.
As for the sliding gallery, you can add it to your main movie or have it as a external swf and use the loadMovie action to load it into the main movie.