I have two questions.

Firstly;

идём на кухню

Why на and not в? My rule of thumb in these cases is that if it is something you can go inside then it should be в. And на if it is something you go to the edge of. (For example; ходить в комнату, смотрит на его). Obviously either wrong - or at least wrong in this case?

Secondly. In general terms am I correct that if I go в something then when I go away from it it is из. And if I go на something then when I go away from it it is c. Is this correct?


спасибо