There is no such thing as an EF6 tornado. The scale only goes as high as EF5, which is open ended with no upper bound.
Most buildings struck by the full force of an EF5 tornado will be completely destroyed. Smaller buildings such as houses and restaurants will be completely swept away. High rise and mid rise buildings will be structurally deformed and may collapse.
There is no such thing as an EF6 tornado. Estimated winds for an EF5 tornado start at just over 200 mph and have no upper bound.
No, the maximum rating is EF5. The primary factor in rating a tornado is damage, and since EF5 damage is total destruction there is no room for a higher category. Also, there is no upper bound for EF5 winds; any tornado with estimated winds over 200 mph is an EF5.
A tornado rips building by the wind speeds and other debris that the tornado is swirling around, so there are lots of things that a tornado can do to a building.
Theoretical winds for an F6 tornado are 319-379 mph. However, because tornado ratings are based on damage, the highest a tornado could ever be rated is F5. So the F6 rating is purely theoretical with no applications in the real world. On the enhanced scale there is no EF6 level theoretical or otherwise.
people get injured or killed in a tornado whether they were close from the location of tornado or they have poor building anchorage so this poor building will destroy which will hurt or kill the people inside that building.
Build it underground.
Unfortunately there is no way to prevent tornado damage, but it can be reduced with improved building standards.
When you see a tornado, go into a secure building or if there are none near you, huddle in a nearby ditch.
The best place to be in a tornado is in an underground shelter, preferably one not directly beneath a building.
People can limit tornado damage by building home to higher construction standards.
If you are too high to get to the bottom floors, go to an interior hallway or better yet, a stairwell towards the middle of the building. The idea is to put as many walls between you and the tornado as possible. Stay away from windows as the greatest threat in a high rise building in a tornado is flying glass.
No it can not because bits going to most likely going to tear up the building. Even if the building is not significant damage, the tornado itself is very large by comparison, extending at least a mile upwards.