As far as I know, bmps don't even load into browsers. You've got to convert them to jpegs or gifs. Jpegs look better I think. Also, Flash converts to jpeg before publishing, so I guess it doesn't even matter. Yes, you use a url to target the .swf which you want to load into a target or level. Movie symbols are referred to as targets in action scripting, and levels are like in photoshop. The main movie would be 0, and you can build from there. I suggest using mcs though, because it's easier to start and finish with in case you need to move anything around. It might be difficult at this point for you to change everything to external files, but it's very easy after you establish your template, and then you just keep "saving as" "newfile.swf" in the appropriate directory, and there you go. Also, it will be easier in the long run for when you want to change/add images, and your viewers will appreciate your kindness in terms of download time.
Blended