Answer to "iPad 3rd Gen Digitizer the same as 2nd Gen?"They appear to be different parts (iPad 2 digitizer, iPad 3 digitizer). That said, I've scrutinized the photos from the iFixit teardowns of both the iPad 2 and iPad 3, and darned if I can see any significant differences. The metal shield around the camera appears to have grown a spring-contact on the iPad 3 to improve contact with whatever it touches, but that looks like it. And it would be very in keeping for Apple to use the same part for both iPad 2 and 3 if they function the same way. The logic boards of each of the two even have their various connectors to the screen and speaker arrays in the same spot. So: inconclusive. Maybe we'll luck out and an iFixit staffer will compare and contrast the parts for us.
Answer to "Where is the internal microphone on the iPad 3?"Still behind the iSight camera on the rear panel.