The west is far less sunny than the east, so it is very hot in the summer. The northwest wind blows in winter and it is colder than the east.
The heating on the attic depends on the situation. Some buildings have heating installed on the attic. On the contrary, it is the coldest and the top floor is even hotter in summer
It is good to have a window in the toilet, but it is best not to buy a top floor that will cause water leakage and cause trouble