Hi Kamal, if the camera is only connected to a standard network switch or directly to your router then yes it will still need a PSU, but if it is plugged into a PoE switch or Injector then that will provide 'Power over Ethernet' and allow you to run the camera with the single network cable and no power cable.
Hi Anthony, the difference is simply how much the camera is able to see, 2.8mm is a wide focal length (about 90 degree field of view) and 4mm is narrower. Check this page on our forum for examples of what each focal length will look like - forum.use-ip.co.uk/threads/hikvision-focal-length-differences.711/
Hi again Anthony, I don't know of a way to turn the LED's off, quick search online seems to suggest most people just put tape over them :) I know it's a bit of a rough solution but at least it works
Hi, Hikvision uses an app called Hik-Connect and it is available for both Android and iOS, in terms of PIR you may be able to turn on PIR via the app but to set up the alerts and how you would receive them, that has to be done via a browser. I hope that answers your questions