These are useful suggestions, and they are not documented anywhere, as far as I know. I have seen the URL command document for other cameras, and I can confirm that it does not apply to the DCS-2230.
The command I would most like to have is the ability to turn a programmed event on or off. For example, I would like use a smartphone to turn on motion detected recording when I leave the house, and turn it off when I return. If anyone knows a way to do this, I would like to hear it. At this point, the best I can do is http://username:password@ipcamaddress:port.setup.htm.