Yep! We support ActionCable with both Passenger and Puma configurations.
You'll need to make sure your domains are added to the allowed request origins list otherwise ActionCable won't connect in production. https://guides.rubyonrails.org/action_cable_overview.html#allowed-request-origins
Yes, but we don't officially support it just yet. You'll need to run the gRPC and WebSocket servers as their own processes and restart them during deployments as necessary.