58?! Damn, that's uncomfortably cold. The coldest I've ever had our house, while I've been in it, is just under 61 (16 Celsius) and we've not had any issues of beeping smoke detectors (wired). They do beep when the power goes out and then again when it coms on.

Apart from replacing the detectors with a different brand, I also recommend making sure to keep room doors open all the time as well as running the HVAC fan at all times to help circulate the air in the house. You're seeing an enormous variation in temperatures between floors, and to me, that's a much bigger problem and implies a poorly designed (and/or implemented) HVAC system.

You can try to close vents strategically to improve air flow to certain parts of the house and you can also try an remote thermostat to monitor temperatures on the top floor. If airflow is low from some vents you can also install in-line duct fans to help pull more air. You may also consider getting in another HVAC company to independently audit the system - it just doesn't sound right to me that you'd have that kind of variation from floor to floor.