Question: I admit to a level of ignorance. Can you refer someone like me to a URL where I can learn more about RSS and its raison d'etre?
There are lots of URLs, but probably no single place to start to gain an understanding of RSS and what it's about. So here's my humble effort to help.
RSS is an XML-based syndication format. A site produces news in both HTML and RSS. Examples include the BBC, InfoWorld and The Daily Princetonian. Thousands of weblogs support the format. Then people can subscribe to these sites using software designed for that purpose, known as an aggregator or reader. The advantage to the publisher of RSS is increased circulation for their stories. The advantage for the reader is that he or she can read an order of magnitude more in the same amount of time. It's not uncommon for people to subscribe to hundreds of RSS feeds. If you were reading hundreds of websites every hour you wouldn't have time to do anything else!
Question: Are the namespaces specified in the directory the only namespaces allowed in RSS 2.0 by the current version of the spec? Or can any namespace be declared and used?
Any namespace can be declared and used. The spec actually doesn't make specific mention of that list. It's just a list of the ones we know about. It'll grow over time. But it's not restrictive, you can use any namespace you like.
Question: I'm really confused in places like the Creative Commons license, which is xmlns:creativeCommons in the spec, and xmlns:cc in other places that I've seen it (and has a different URL, too). Are these actually different namespaces, and one is valid in RSS 2.0 and the other not?
They are different namespaces. There are two Creative Commons namespaces, one was done for RDF, and since RSS 2.0 is not RDF, it couldn't use it, so we created another that didn't assume it was embedded in an RDF file. At the time I explained to my friends at Creative Commons that they could have supported syndication without taking sides, but I don't think the people in charge fully understood that they were doing that. In any case, we've got two namespaces now. C'est la vie.
Question: I've run my feeds through the validators I could find, and all of them seem to like it well enough -- but I'd really like to be compliant with the spec itself if possible (and perhaps even "unfunky", though I still don't really know what that means.
Here's the definition of "funky" from Dave Winer's RSS 2.0 Political FAQ: "A feed is funky if it uses extensions to provide information that can be expressed by core elements." It goes on to explain why being "not funky" helps to increase interop and make it easier for programmers to write readers and aggregators.