Jon,
Welcome to the wonderful world of RSS, XML, and XSL!!! I must say at the outset, you've chosen a very difficult and challenging newsfeed to decipher and use. It is a challenge to go through. As you know from reading my posts, the first step is to examine the newsfeed source, view the code, and work through it. I really can't go into all of the details in this post, but will promise to take this challenge up on my seldom used blog, where I have more space to use for such madness.
The keys to doing what you want will take some programming effort and skill, so you really need to bone up on all of the components, RSS, XML, and RSS to customize the feed in the manner you want. There are no short cuts, like you didn't know, right?
Anyway, for starters, take the bits that are easiest and work from there. For example, there are many posts dealing with how to limit the number of entries. Take the code for that and store it somewhere for later use. Now, I'm really assumming you want to learn how to do this stuff, and not just get a freebie xsl.
So, first step - examine the feed to see what type of feed you are messing with. Here's a start - the following code contains info that identifies the type of RSS feed being used, and the namespaces used in the feed for the various attributes it contains.
<?xml version="1.0" encoding="ISO-8859-1"?>
<rss version="2.0"
xmlns:content="http://purl.org/rss/1.0/modules/content/"
xmlns:wfw="http://wellformedweb.org/CommentAPI/"
xmlns:dc="http://purl.org/dc/elements/1.1/" >
Now, the feed is an RSS v.20 - but that can be misleading, so we look at the namespaces contained in it, and find a reference to an RDF namespace. Why is that important? Well, because it's a key to getting the description info you want without all of the muck. I take the http reference and visit the site to find out just what is being used. In this example, it's pretty easy - the attribute content is being defined.
Now, this is a start and I'll give you more in the morning, as I'm losing power to my laptop and on the bus at night, pretty scarry stuff, hauling a laptop and taking a bus, but things are what they are today.
Promise to follow up, hope this gives you a bit of insight and help.
Cheers