dynabalance mode and some other problem

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So What is this mode exactly? If i want to implement my own PID controller can i use the MSP_SET_MOTOR myself and fly the quad with MW FC? As far as i have heard i can use MSP_SET_MOTOR for only dynabalance mode for individual motor speed check etc ( i dont know much about that mode). Also do i constantly need to send the MSP_SET_MOTOR or MSP_SET_RAW_RC values even if they are not changing? I heard sending the values within 1 sec is mandatory for MW FC? Am I wrong ?