Lost my Macbook pro with retina display. How do I find out if Find My iDevice is enabled on it?
If you can see your MacBook Pro with Retina Display in iCloud, it has been enabled. The reason it is showing as offline is because it is either (1) shut down and not connected to internet, or (2) the device has, somehow, already been wiped, with the first option being much more likely in this situation. Computers are particularly vulnerable to this type of situation because they don't have a constant data connection like an iPhone, or data-enabled iPad, often would. The user must boot the laptop and connect to a wifi before Find My Mac will know anything about it's where-abouts or be able to perform any actions.

The first, and main thing to do is to select the the "Lock", or "Erase" option. If it is a neighborhood kid and you think some noise might provide truth, you could always do the play sound feature. This plays an alert at maximum volume. You should probably use this sparingly, and only activate it, for example, if you are within earshot of it. Chances are the user could take quick actions to dampen the sound. 

As for the "Lock", or "Erase" option, it will do this as soon as the computer is connected to the internet. Obviously, if they never connect the computer to the internet before wiping it, then the Lock feature won't do any good, but at least if they do, it will help you.
Good news for you is you can erase your Mac and still be able to locate it with Find my Mac. (Another helpful Q&amp;A on that).
And yes, you will get an email when any action occurs on your Mac - such as it being locked or found.