Max Shutter speed
Pentax K-3 III Monochrome can shoot continuously at max speed of
12.0 fps and has max shutter speed of
1/8000 sec. K-3 III Monochrome also has an electronic shutter which can shoot silently at max speed of
1/16000s. 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 K-3 III Monochrome doesn't have a built-in flash but it has a flash shoe for mounting external flashes.
Focusing
Pentax K-3 III Monochrome features both Contrast Detection and Phase Detection autofocus (AF) systems which ensures speed and accuracy of focusing in most situations. The AF system has 101 focus points and 25 of these sensors are of Cross-type. Cross-type sensors locks focus faster and more accurate compared to single type sensors.
Pentax K-3 III Monochrome also features
Face detection AF where it intelligently detects the faces in the frame and locks the focus automatically.