It's worth pausing here. Look carefully. That's RSS data in JSON format. (I was not the first to do this, thankfully, I had prior art to look at. And a very nice validator to work with as well.)
4. You can also get the long-poll version in JSON, though it's harder to demo. You should call this from a loop in a script to test, or from a browser-based AJAX app. The call below will timeout after 3 seconds. The default is 180.