Since my physics is at a very basic level, I don't understand 3 things:

1.The drag seems to be always higher than the thrust for the same RPM. Doesn't that mean that the quadcopter can't move, because the drag will always stop it?

2.What is $k_M$?

3.What is $k_F$?

The source is here at 2:22.

$k_M$ and $k_F$ are calibaration constants - I mean you could try to use fluid dynamics to estimate them but with complex rotor shapes it would be much more accurate to measure them.