P4 + Litchi (waypoint mode): land in emergency

[PeteM]

Phantom 4 "driven" by Litchi in waypoint mode.

How immediately stop the drone during the mission?

Once the mission has been interrupted (and the drone is hovering in the air), how do you resume manual controls?

If the drone is far from the take-off point (so driving it home manually is difficult) how do you get it back to the take-off point automatically?

 

[Meta4]

Phantom 4 "driven" by Litchi in waypoint mode.
How immediately stop the drone during the mission?

In any automated flight mode, whether RTH, Litchi or one of the DJI Go intelligent modes, flick the flight mode switch to atti and back again and you cancel the mission.
The drone will just sit there hovering.

Once the mission has been interrupted (and the drone is hovering in the air), how do you resume manual controls?

You just push the joysticks in whatever direction you choose.
The drone is now under your control.

If the drone is far from the take-off point (so driving it home manually is difficult) how do you get it back to the take-off point automatically?

driving it home manually is difficult ?? I'm not sure what to make of that.
But you could always initiate RTH with the screen button, the controller button or by switching off the controller.