How can I create and configure a swap file for MCNlive, ideally to a fixed hdd partition? I haven't been able to find any info on it...

I have never worked with swap files (rather than a swap partition), maybe this article can help you?
http://linux.about.com/od/linux101/l/blnewbie4_2_13.htm

Great, it worked! Thanks ! The MCNlive forum has done it again...

Do you happen to know how one checks on the status on a swapfile, its usage etc.?

Doesn't it work with the "free -m" command?

Indeed, that's it

Whenever I shut down the system with a 1GB swapfile it takes ages for the system to "turn the swapfile off". Is that necessary? What does the system do here?