If MyCanal is an app in Googe play, then you will likely be able to install it to chromecast.

If you mean Mycanal from Canal +, then the answer is yes, it is available. I've just checked it in the Play Store. It is compatible with Chromecast and Google TV

Yes, MyCanal is available as an app in the Google Play Store and can be installed on the Chromecast.

No, but if the app is available on Google Store, you can download it on Chromecast.