Take a look in the Microsoft.Xna.Framework.Media class - there are collections for Picture and Songs and playlists...
There is no support for video in the CTP and its not announced if that will be fixed or not.
Check out the MediaPlayer.GetVisualisationData for your second question. Its not the actual sound - but its information that you can use for that application.
The ZBuffer - News and information for XNA and Managed DirectX