The site soundscreen.com has quite a bit of information about Darwin, including the best explanation I've seen for embedding content. You can also look at the test page that I set up at
http://myhopechapel.net/~joe/streaming.html
As for ports, you need 554 and 7070 open. If you enabled streaming over http, you'll also need port 80. You also have to make sure your firewall doesn't block outgoing UDP packets in the range 6970-6999. If you are behind NAT, you need to make sure that you modify the streamingserver.xml file to include your public IP address, and even then, depending on router, you may never get it to work. If you want the streaming admin server accessible, you should open port 1220. Port 8000 is used for MP3 broadcasts.
Have you joined the apple mailing list for DSS? I haven't been monitoring it very closely for the past few weeks to know if you've asked anything.