first thing first , on the middle vent there is two vent actions. one is to open close the vent and the second one has blue to one way and red to the other. select blue for colder air. for the coolent level , if you didnt get the rad done at a bmw guy than i suggest you check the coolant level, its a very very common thing when the system isnt bled right and proper amount of coolant isnt added.
as for the top, im really not to positive what i could be, but i will hopefully get back to you on that.