For me though please don't add sound. That scares me from any site, I can handle a little flash but makes sure if flash ins't intalled that the person doesn't get undesired results. for example a FF browser on unix may not like the way you put the flash in so just do a little testing to make sure you aren't abondoning anyone or freezing their browser.
Also see the new IE7 flash implementation that will have users "click to activate" flash content.
that "implementation" you discussed is a necessary evil as a result of a lawsuit microsoft is going through, once the courts are done with it, it will be removed. and its not IE7 its all versions of IE.
The car zooming accross, will be with a transparent background and over the current content. Ive tried this but the flash is just inserted in between, not on top of the body text. How can I get it on top?
Also I would like the page to load nice and fast as before. Presumably I can make the browsers load it last. Is there any way to do this?