Oh dear... That's a tough one.
If your landlord isn't "the greatest," then you may not get much satisfaction there. But I would try anyway, first.
I would not approach the unstable neighbor.
I would invest in some potpourri and air-fresheners...as well as a newspaper, to check the classified ads for a new apartment.
Though, it seems like you knew there were smokers in the building, when you rented there. The time to decide if that would bother you, was prior to signing the lease.
That being said, however, I wouldn't appreciate my apartment smelling like the corner bar either. Is there anything in your lease that prohibits smoking in the apartment? If so, you may have some recourse.