Sticking with the answers from local brokers will serve you well. Local customs and regulations are in play with a multifamily. Asking the most basic questions, and you may have done so already, is your most prudent first step ...Does the smoker know the pollution is drifting to others? ...and... Is the landlord aware of the heat problem? Then, you will want to consider the various strategies available to you. Warrant of Habitability is the correct clause. Your landlord is in a weak position by not providing heat. Moving out is expensive and inconvenient so I hope you find an amicable resolution!