To check the firmware version go to ‘Settings’ > ‘About Device’ > ‘Build Number’
To update the firmware go to the built-in ‘User Care’ APP where you can automatically download and install new firmware updates as soon as they’re available.
It's 1080p when previewing, and could be 640p output when having video call.
It's becuase build-in speakers could help to improve the audio output quality when having video call, and if the audio output from TV, there maybe a little echo.
Yes, all of the Android devices have build-in Kodi 16.0 with many videly used add-ons.