You can set your iPad to automatically download new music, apps and books made on other devices by following these steps:
1. Navigate to Settings > iTunes & App Stores on your device.
2. Tap "Sign In" if you're not already signed in to the iTunes Store.
3. Enter your Apple ID and password.
4. Tap to enable or disable Automatic Downloads for each content type.
You will need iTunes 10.3.3 and iOS 4.3.3 or later, or iOS 5 or later for the iPhone CDMA model to enable automatic downloads.
You can also enable automatic downloads over a cellular connection below under the iTunes & App Stores settings.