Wow, chill, Kindergarden is teaching them social behavior, motoricity, basic understanding of music, the importance of a daily structure, etc.
Depending on the Kindergarden, preschool courses are given to the older kids who are just about to enter elementary school, where they focus on e.g. counting, drawing, experiencing homework.

Not with a 3cm girth tho

Just no. On all levels. No.

No, the only domestic flights using A380 are taking place in China.

There were several approaches for two level seating, some where very interesting and actually possible to install in an aircraft, but there are several regulations not allowing this to happen. To name just two, there's the question of evacuation in emergency, which would get complicated and slower, the other one that for a 16G certification, the materials would need to be very heavy and the fixation of seats to the fuselage would increase the weight furtherly.
Other ideas in this direction were "standing seats" for short-haul flights e.g. this one https://www.express.co.uk/travel/articles/947825/plane-seats-standing-passengers-flight
But again, airlines want their seats to have a 16G certification...

Generally we can agree that it's amazing how mankind could find a way to outplay gravity and fly from one continent to another and then make it to the most miserable travel experiences in existance.
If you're struggeling between 333 and 242, I recommend the A380 with a 343 setup. ;)

Yeah, kind of, the size of the B777-300ER is the same size as A350-1000, but the Airbus has a higher seat capacity due to 1 door less.

That would be the Airbus A380, which definetly isn't shown in this picture.

And still they're building their houses of wood. Europe has storm, as well with high wind speeds, but the damage is less.