New to CCTV - some questions before purchase - Temp, Storage, Angles, IK10

SecCon

I am going with Reolink's products for my current surveillance needs but if you would allow me a few questions (since I am not currently a customer I do not seem to be able to contact Support).

I will need 4-6 cameras, depending on placement, viewing angles and responses below. All will run via PoE and some will need to be IK10 "Vandal proof". All connected to my own Switch on a VLAN on my own network within my own firewall.

Temperature span, I find -10 Celsius a bit high, we frequently have lower temperatures where I live... I realize it is a "default" limit, but I would really like to know the real temp limits in cold weather, if anyone can contribute with their experience?
I stumbled on the possibility to store the media via FTP, I have my own server and can store TB's if needed, but I do not want to risk warranty or anything like that using apps Reolink do not approve, so how would that be done?
Looking at https://reolink.com/product/rlc-843a/ there are some number in degrees I do not understand. The FoV angle is seemingly low, only 100 degrees, but how do the other values affect the REAL image I can see in the camera: Horizontal: 100°- 31° Vertical: 55°- 17° Diagonal: 123°-39° ? If FoV is decided by 100 degrees, well then I need a 130 degrees camera ? (Needs to cover an area of about 50 square meters and I guess it need to be placed in a corner to cover everything, rather than in the "top center" of a wall, at about 3 meters height.
Looking at https://reolink.com/product/reolink-duo-3-poe/ it would be a better solution, but it is not IK10...
Can you rackmount a NVR?

And one last question, is there any licensing costs for using Reolink or the camera cost is the only cost?

Thanks for reading and looking forward to your answers...

Crimp On

FTP is a feature built in to the RLC cameras. (not the battery powered cameras). I use it to store recordings from 8-10 cameras using FileZilla FTP server. Provides backup for the camera SD card and (I know this is goofy) allows me to use VLC to view motion recordings.
There are no fees to use Reolink products unless one subscribes to a "cloud storage" plan (I have not)
Looking forward to someone reporting actual temperature experience. My guess is the cameras might function at lower temperatures, but if they don't then Reolink's answer will be "told you so."

SecCon

Actually went ahead and bought 4 cameras, two Dome and two "turret". RLC-843A and RLC-820A.
Also found two brackets for the domes, which was a welcome bonus, since it makes the mounting easier.

Looking at doing a vinyl wrap or some such on them since there was no chance to get them black.

New to CCTV - some questions before purchase - Temp, Storage, Angles, IK10

@seccon Go to Amazon and search for WiTi 4.7 inches Wall Mount Bracket for Dome Security Camera.