No, it is not true that you can switch it off at the thermostat. But you can set the temperature down and up, but only in 1 degree increments. At least that's the case with my Tado thermostats, which I bought 1.5 years ago. You can switch them off completely via the app and also adjust them in 0.5 degree increments. The app is much more convenient anyway because you can also create schedules.

Yes, this can be done directly via the thermostat.