I have a 520A here myself and that one also comes with the metal bracket. Although, with these 4K cameras, they don't really play nicely with PC NVR software like Blue Iris. I might just get their NVR instead.
No security camera will stream at full rate for various trains. It records in 4K for viewing later or you can watch live in 4K with a monitor at the NVR, depending on the equipment.
Can 4K Reolink cameras be connected to home assistant ? I feel as though I read something that the Reolink 4K cameras can’t produce an RTSP stream which works with home assistant