Using QGC with PX4Flow/PH2.1/TeranRanger One/ Basic setup

Hi there,
after trying out the APM Flight Stack I swapped over to PX4. The reason is because I didn´t get rid of Bad OptFlow Messages in Mission Planner. So now I am asking my self what should I do configure in QGC (3.2.5) for the Basics. At Ardupilot there is a nice Wiki about the configuration and testing. For the PX4 Flight Stack I haven´t found one so I am asking here :-).
I am using a quadrocopter and I did already the Sensor configuration for the flight Controller. But now I don´t how to congfiure the Flow Sensor.

I started with the orientation of the Flow Sensor. I mounted it with the X in Front to the Vehicle. There is the first confusion, because QGC is saing the Orientation is than 0°, so no Rotation. But this link is saying something different. At the moment I am going with the describtion of QGC, so with No Rotation.

An other thing is how can I activate the flightmode to keep the position by using the Flow Sensor and the LIDAR? I am not using GPS at all. I don´t want to crash my quad right at the beginning caused by wrong configs.

Thanks for helping me out!

These questions are more related to firmware setup/features as opposed to using QGC. Hopefully firmware folks can jump in.