A SWF file (that with a swf extension) is a compiled, viewable only, flash file. You would use this format by way of means of presenting through the web. You can export this file along with the HTML file in Flash MX if you have the .fla file. By placing the .swf files and .html [...]

A FLA file (that with a .fla extension) is the source, or editable version of the flash template. From here you can modify your template and produce FLA files for presentation via the web. With the FLA file, you can export the SWF files.

First you should start by identifying the place on the Timeline that you wish to “goto” when a user presses the Skip Intro button. Then add a button somewhere on the stage. Then, select the new button and open the Actions panel. After that, add a gotoAndPlay() function call within the on(release) button event. Pass [...]

Yes. Please following these steps to change it:
1. Open the library (press f11).
2. Find the background graphic (the file name varies, depending on the
different template)
3. Double click that graphic file, in the timeline click each key frame and
replace the background picture to whatever you want (import another
background picture).

Press Ctrl+L on your keyboard to open the Library dialog box. In the Library, select the bitmap you would like to change. Double-click the small icon next to the bitmap name. This will bring up the Bitmap Properties dialog box. Click the Import button and select your picture(*.jpg). Click OK to import the file.