You can download your own themes search
www.google.com, you can change the picture of the background yourself in the album option under programs menu.
To increase battery life dont leave BT, WIFI and IR on and set the PDA up to turn the backlight off etc. Make sure you dont leave programs running in the background, press the bottom right button on your iPAQ the one with the black arrow and you will see a list of programs running in the background. Close these off to free up memory and to prevent your PDA from crashing.
Hope this helps