Does the Nexus 7 have a LED flash for its front facing camera? Can somebody point me to some documentation online that states whether this is true or not?
As a Nexus 7 owner, I can confirm for you that it does not have a LED flash for its front-facing camera. In fact, off the top of my head, I can't think of a single device that does.
Documentation of a feature that isn't present is going to be hard to come by. A good verification of this fact, however, is in ifixit's teardown pictures (see steps 12 and 13). Camera and light sensor, no flash.