Max Shutter speed
Canon G7 X MIII can shoot continuously at max speed of
30.0 fps and has max shutter speed of
1/2000 sec. G7 X MIII also has an electronic shutter which can shoot silently at max speed of
1/25600s. 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 G7 X MIII doesn't have an external flash shoe so you are limited with the built-in flash.
Focusing
Canon G7 X MIII features a Contrast Detection autofocusing system. Canon G7 X MIII also features
Face detection AF where it intelligently detects the faces in the frame and locks the focus automatically.