Not sure if these will work on SE, but you can give them a shot (they are all freeware):
PMH Pocket PC Plus allows you to not only see what is playing in WMP, but you can also play, pause, or stop the music from your today screen.
tdlaunch allow you to put shortcuts to your programs on your Today Screen.
Today Weather adds a weather plug-in to your Today Screen.
As for the calendar and battery meter apps, there are a million programs, so just do a search on
www.freewareppc.com!