For starters, is it obvious which building you can go inside?
Not really. Is the top left door an automatic door or a locked door?
Do you think it might look a bit too out of place with the other buildings?
The "mediocre bombs" building looks out of place but that seems to be intentional.
What I would like to know is, is it obvious where the back wall is and where the exit is?
Yes, the back wall is on the top of the screen and the exit is on the bottom.
Same as before, is it obvious where the wall is?
Yes.