Well, actually the top floor will have a smaller angular size if you're at ground level because the top floor is further away from you than the bottom.

Nope. It's bigger.

No.

Let's imagine you're a a thousand feet away from a building. And for the sake of simplicity let's say each floor is 20 feet high and your viewer height is 10 feet. That means your view of the bottom floor forms an isosoles triangle, the base of it is 20 feet and the long sides are 1000.05 (using pythagorus, it's the hypotenuse of the right angled triangle 1000 feet long and 10 high). Using a triangle calculator the angle at the point of that triangle, in blue, is 1.146 degrees, which is your angular size.

You can also use Pythagorus to find the lengths of the sides of the triangle to the top floor. I've assumed 6 floors.

So those lines are the hypotenuses of the right angled triangles 1000 long and 90 high for the bottom line and 1000 long and 110 high for the top line. The base of that triangle is also 20 and the angle at the point of that triangle, in green, is 1.135 degrees. And that's the angular size of that floor, which is smaller.

This is obvious just be thinking about it. If you're looking up at a tall building then the higher floors appear smaller because they're further away. It's the same principle here.