Just to clarify where to light:
If we live on a low floor apartment (2nd Floor) likely under 20 Amos.
Our balcony faces the street with a window next to the balcony to the right which also faces the street.
Our entrance door is internal and the building rules will not permit lighting by the front entrance to the building.
When saying a bracha it would be on candles overlooking the street and that there is no advantage to lighting on a balcony rather than by a window (but the important item is that more people can see).
Should one also light candles by the entrance to the apartment?
If you can light outside the door to the balcony, in a way that the candles are visible from the street, this is ideal. You would then be able to fulfill the hiddur of lighting by the door (and beneath 10 tefachim), as well as having the candles clearly seen from the public domain.
If this is not feasable, light by the window.
I understand that the option of lighting by the entrance to the apartment is not an option, based on the building rules you mention.