Morning Stephan, it’s early here and just having my coffee.
You cannot brake and I’m not sure about other functions as Im just learning about Zwift. When the video is playing, the riders “ride through” you and you through them. The video isnt perfect. I don’t know about crashing yet lol.
As far as I know, if you have the Cog, it must be used through Zwift and the Clickers for it to shift the gears and the pedal resistance to be felt. If your friend used a cassette instead of the Cog, then it could be used without Zwift and apparently can be used through Swoosh or Rouvie. The kid from my LBS told me that, but I haven’t tried it. Also not sure about riding it through the Element bike computer.
For $20 a month membership to Zwift, it’s cheap enough for something to watch and interact with when I’m on the indoor trainer.