I wear SmartWools socks to temps below about 25 then I add toe covers. I've ridden with wind chills down to 6 and my toes stayed fairly warm. As for the cough, I'm asthmatic so I may not be of much help. I wear a balaclava that covers my mouth anytime I ride in temps below freezing and even some times when the temps are warmer but I'm riding in a headwind. You could try some Primatine (sp) Mist (OTC inhaler) after your ride and see if it helps the cough.
Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well preserved body, but rather to skid in sideways, champagne in one hand, strawberries in the other, body thoroughly used up, totally worn out and screaming: "Yeah Baby! What a Ride!"