Max Shutter speed
Sony A9 II can shoot continuously at max speed of
20.0 fps and has max shutter speed of
1/8000 sec. A9 II also has an electronic shutter which can shoot silently at max speed of
1/32000s. One thing to keep in mind is that electronic shutter may cause rolling shutter / jello effects, and also banding issues under artificial light on your images.
Flash
Unfortunately A9 II doesn't have a built-in flash but it has a flash shoe for mounting external flashes.
Focusing
Sony A9 II features both Contrast Detection and Phase Detection autofocus (AF) systems which ensures speed and accuracy of focusing in most situations. The AF system has 693 points to choose from. Sony A9 II also features
Face detection AF where it intelligently detects the faces in the frame and locks the focus automatically. In addition to the face detect AF, A9 II has a more sophisticated feature called
Eye Tracking AF which detects and locks focus to the selected eye of the person in the frame accurately and tracks as the subject moves. Eye tracking AF of Sony A9 II is a perfect feature for shooting portraits and is especially useful when fast lenses are used and the depth of field is very narrow.