Godox AD600Pro Witstro Flash and Nikon Wireless Trigger for Nikon Cameras Kit

The Nikon SU-800 can only control Nikon speedlights that offer optical triggering for TTL.

I don't know exactly what you mean about beat the sun. I use mine with a reflective umbrella as a fill flash outside and the flash has plenty of power. I don't try to overpower the sun.

Yes, this Godox system is Optimized for High Speed Sych, which is controlled by You controlling your Camera shutter speed.

Yes

The Impact Sync Cord Male Mini (3.5mm) to Male PC (16') B&H # IMMMPCM16 can be connected to this monolight and the sync terminal on particular cameras instead of using the transmitter. That would make the monolight completely manual at that point.

You may use any standard PocketWizard radio transceiver/receiver, such as either the PocketWizard FlexTT5 Transceiver Radio Slave for Nikon i-TTL Flash System, B&H # WIFTT5N, or the PocketWizard PlusX Transceiver, B&H # WIPWPX, connected to the 1/8 (3.5mm) miniphone sync terminal on the bottom of the Godox AD600Pro Witstro Flash using the PocketWizard MM1 Miniphone to Miniphone Cable -12 , B&H # WICMM16. However, do note that this will simply allow you to wirelessly trigger the flash. You will not have TTL or High Speed Sync capabilities, and you will have to set the flash output power manually on the monolight, as there is no option to wirelessly control the flash output power using the camera-mounted remote.

This is for one flash and a transmitter.

Godox has not confirmed that their Nikon radio transmitters will work in TTL mode with the Hasselblad X1D II 50C Medium Format Mirrorless Camera. However, most users who own the Hasselblad X1D II 50C Medium Format Mirrorless Camera state that Godox strobes do not have TTL compatibility when used with the X1D II, but you can set the transmitter and flash to manual mode and set the flash output manually, which would be compatible for use with the Hasselblad X1D II.