I wanna know how this works. Is it a cell that seamlessly intergrates with the world, or is a building's interior simply a part of the wasteland? Will this be good for hide and seek and AI?

Also, I want to know if I can blow up a house, or block the exits and set fire to it.

Ehhhhhhhh we...have no indication of whether we can or can't.

Probably not take a look at the buildings in the trailer. Apart from the first house, the windows on the buildings don't look transparent.

Probably not, because of how Bethesda has always designed their worlds. We may get single houses that aren't in separate cells, but definitely not large interiors like skyscraqers or vaults.

A "cell" is its own discrete unit ,existing in its own separate "universe", and it takes special processing for activities in one cell to affect anything in another cell.