Cool - well done for the persistence, and getting NOAA's involvement!

Just a quicky ... which may help...

FTP access for the Overlay image should be possible!

The normal (http) mechanism would be something like:
<icon>
<href>http://bbs.keyhole.com/ubb/z0302a1700/etna.jpg</href>
</icon>

The FTP version should be:
<icon>
<href>ftp://username:password@ftp.mysite.com/pub/blah-blah/filename.jpg</href>
</icon>

That would work if the FTP site required a username and password. If it didn't (ie, was anonymous) you'd probably be able to get away with just:

<icon>
<href>ftp://ftp.mysite.com/pub/blah-blah/filename.jpg</href>
</icon>

or maybe:

<icon>
<href>ftp://anonymous@ftp.mysite.com/pub/blah-blah/filename.jpg</href>
</icon>

Hope this helps - looking forward to seeing this go live. If I can help further (or if you want me to have a check-over of your KML, or turn it into KMZ), just let me know. Cheers!