Max Shutter speed
Nikon D800 can shoot continuously at max speed of 4 fps
and has max shutter speed of 1/8000 sec
D800 has a built-in flash, and it also has a flash shoe to mount your external flashes too.
Nikon D800 features a Phase Detection autofocusing system. The AF system has 51 focus points and 15 of these sensors are of Cross-type. Cross-type sensors locks focus faster and more accurate compared to single type sensors. Nikon D800 also features Face detection AF
where it intelligently detects the faces in the frame and locks the focus automatically.
You can download Nikon D800's User Manual here