Here is a beginning course in Windows Mobile and also a Instructional guide :
http://wiki.modaco.com/index.php/Get...Windows_Mobile
Also take a look at this it is a very detailed and helpful guide
http://forum.ppcgeeks.com/showthread.php?t=17473
Alot of Applications that are compatible with the Sprint are also compatible with other CDMA carriers the main thing is that you gotta remember to read instructions to everything posted...This will be clearly discussed if non compatible...
I wouldn't feel pressured to jump right in a start customizing until you read up, understanding what you are getting into..