Tim is right. There is no way to monitor overall usage of the iPad.
However, you can protect the iPad to a reasonable extent and monitor Internet activity. You will need to
- restrict apps (install all the apps you need and lock the App Store),
- restrict Safari and use the Safe Browser app (from Mobicip, which does give you a way to restrict Internet access by category, websites, or by time, and monitor the browsing activity), and
- restrict other content accessed through iTunes.
You may find the detailed tutorials on the Mobicip helpdesk useful to set this up.