As above. Simple to just push if going away for a few days rather than turn each stat down
No not on the moment. This topic probably already came up in the suggestions catergory. I suggest to vote on this suggestion.
You can do this via IFTTT buttons though.
Ok cool. I need to get to grips with IFTTT
Here's the IFTTT tado heating section - https://ifttt.com/tado_heating
...and the "turn heating off" applet - https://ifttt.com/applets/pDcz7gVi-turn-heating-off
You can configure it to work with a specific room, or look at the bottom of the list and you'll find an item that includes all of your rooms which you can use to set up one action to turn them all off.