Read the doc. Use the MP motor test to determine the values. Slowly increase the throttle % in MP motor test until it start to spin. if you found the deadzone of the ESCs was 7%, set MOT_SPIN_ARM to 0.09 (i.e (7 + 2) / 100).
Can try 1120 - 1920 us
High chance yes, it was used in DJI S900 very old model drone.