First I created my own CMS, but then I decided to use an existing blog engine (blogengine.net in this case), because I wanted to have comments and other stuff in the future, and it is not worth maintaining the whole cms if you can just tweak some things in an existing one.
Then there is the mp3 thing.
For this I've created my own app. It both takes text from mises.org, converts it into mp3 and posts it as a post on the blog.
As for RSS - it's there on the top menu - no icon - sorry. Will add it sometime in the future ;-)
Hope this answers your questions.
Please feel free to ask if you want to know more.