Hi,
You are the first Stephan spelt this way I have talked to!
My name is not Steven, as some people think, it's Stephan, with an "a", which is quite rare, or so I thought!
Anyway, your questions...
You can point domains to seperate directories for the fee of $2.50 per domain per month.
So, you would have
www.yourdomain.com being your main site,
then buy seconddomain.com which would actually be
www.yourdomain.com/seconddomain/Users wouldn't be able to tell,
www.seconddomain.com would appear in the browser.
This doesn't use frames by the way, it's done the proper way!
The mail server runs "Exim".
Spamassassin is provided -
http://spamassassin.org/It will mark spam for you, so you can setup a filter to delete it/move it into a spam folder so you can read it, check it's not spam, then delete it.
Spam filters can be set up from your control panel.
Quicktime files will work, and stream over the http protocol. It works pretty well, I've tried it before.