The first thing I'd do if I were using that template would be to kill the music. <bork!>
As for replacing content, that depends on whether it is built upon a CMS (content management system) or whether it's based on static pages. If it works in conjunction with a CMS, then you'd be able to to the changes via some sort of admin interface directly on the web. If it is based on static pages -- hardly anything is anymore -- then replacing files with same-named new files would certainly work.
Also, I strenuously recommend against using Flash as the primary element of any site unless you're a flash designer and need to show off your skills. Search engines can't index flash, so you have to use other tricks to get your content indexed. Used sparingly, e.g. for an animated header, flash can be quite effective at adding pop and wow to your site, but the fewer things you have flying around, the snappier your site will feel. I hate having to wait for a site's user interface to catch up with me.
