I have never ever done anything remotely as complex as this. That doesn't mean to say it can't be done.
But as you are doing this from memory

, perhaps if you got closer to your PC tonight when you can get back on the INTERNET then maybe some good person here can talk you through.
If I think I have anything valuable to say, I'll chip in.
However, and in the meantime, 2 points I wish to raise with you are:
Point 1 - Have got "
Ignore 3rd Party CODECS" in Options>Preferences engaged? But be warned some CODECS start fighting for supremacy once they sniff another one urinating on their tree or territory! Personally? For the more exotic CODECS I would finish my project in VEGAS and use another s/w to render to these others. That being said, I HAVE had much success with MOV and MPEGs. DiVX? Dunno . . ..
Point 2- In the meantime, you say you are on Vegas7a? Well Vegas7 is up to version V7e, just thought you should know that.
G