If your iPad isn't passcode locked, you do have to consider all those documents compromised. Chances are whomever stole it didn't care about what you had on it, they wanted the device to make a few bucks. For better or worse, a thief can wipe a device and restore it to 'out of box' state, then set it up as they want. And they can do this in just a few minutes if they know what they're doing. the bad news about this....once the do that 'find my iphone/ipad' doesn't work. The good news however, is that your data is wiped. (of course there was nothing keeping them from going through it if they wanted to before they wiped it)
'Find my' has one weakness in that it depends on the device being on the internet to be located and dealt with. Keep it off wifi and it remains invisible to the program.
The best way to protect your data is to use a passcode lock, and more complex than just the default 'four numbers'. You can also set your device to wipe after a certain number of incorrect attempts. Doesn't stop people from stealing your device, but it does help to protect your data.
These links may be helpful.
How to Track and Report Stolen iPad
Reporting a lost or stolen Apple product
Report Stolen iPad Tips and iPad Theft Prevention
How to recover a lost or stolen iPad
How to Find a Stolen iPad
Apple Product Lost or Stolen
Oops! iForgot My New iPad On the Plane; Now What?
If you don't know your lost/stolen iPad's serial number, use the instructions below. The S/N is also on the iPad's box.
How to Find Your iPad Serial Number