As far as I can tell, RSS feeds only work for the parent folder they point to. For example, if I add new photos to a *SUB* folder of the RSS feed, the RSS feed of the parent folder is NOT updated. Is that how they work?

Sorry, I can't follow your problem. You can call either a feed of all images, of one specific album or with the collection mode of an album and it's subalbums. None of the themes uses the collection mode by default.

Also there are two places where the rss feed is called on each page, within the header (what you see in the browser adress bar) and the one on the page itself. Each can of course be configured differently.

That's exactly what I meant. I want the RSS feed to work just like my other sites. On my blog, for example, the main RSS feed shows updates to ALL parts of the blog, not just a single category (or folder). I want to be able to add new images to a subfolder and have the main RSS feed show the updates...this is how most people expect RSS feeds to work. I hope that's clear enough...

OK, so how do I turn on collection mode? Can you point me to the docs?

Here are the docs of the related functions:
http://www.zenphoto.org/documentation/functions/_template-functions.php.html#functiongetRSSHeaderLink
http://www.zenphoto.org/documentation/functions/_template-functions.php.html#functionprintRSSHeaderLink
http://www.zenphoto.org/documentation/functions/_template-functions.php.html#functionprintRSSLink

Here's what I did -- I changed printRSSHeaderLink('Gallery'... to printRSSHeaderLink('Collection'... in index.php of the default theme that I am using. So far so good right?

Unfortunately, this gives me an error:

Fatal error: Call to a member function getFolder() on a non-object in /home2/worthyis/public_html/albums/zp-core/template-functions.php on line 3465

At first I thought my database was corrupted, so I reinstalled zenphoto. I tried that on a fresh install and it still does not work. Do I need to make sure that all albums are actually in the database? (All I did was symlink the albums in the "albums" folder.)

FYI... the default RSS behavior is a "deal breaker" because it behaves contrary to what is expected (see my comments above). It would be a good idea to clearly explain somewhere how RSS feeds work in zenphoto (to a user, not internally). I would have tried another software if I had known ... Please don't take this personally -- it's just in the spirit of making zenphoto better.

Or wait, could it be that the problem is that some of the folder names use apostrophes? DOH! Not really sure what you mean by "some servers don't support apostrophes" --- it's linux. Linux supports apostrophes in filenames. Seems to me that the problem is the php code, but then again I don't know the internals of zenphoto...