Hi,
Site looks good

. If you want to center your pop up window just add this script to the opening window (and adjust the windowWidth/windowHeight accordingly):
<script language="JavaScript">
windowWidth=300;
windowHeight=200;
if (parseInt(navigator.appVersion) >= 4) window.moveTo((screen.width/2)-(windowWidth/2),(screen.height/2)-(windowHeight/2+20));
</script>
I agree with Nd4Spd and don't think you need a preloader either but I'm sure you could find the help you need at flashkit.com.
I didn't notice the 'about' button sticking but if you want to send me the .fla I'll take a look (is it actionscript or frame-based?).
All the best,
E3