How does it get timed, all IGTs combined or real time? + do you need to have the dlc or just do the heists that are available for free?

So my WR run got rejected for suspected autoclicking, but i didn't autoclick. How can i prove i didn't autoclick?

Subjective, Quantum got an 4:10 (unrecorded) and that seems like the upper limit of this category. Unless a major skip is found, i dont think a sub 4 will be possible.