I wear a Fly rainproof armored jacket with a zip in thermal liner. Its waterproof and windproof. I have also just installed a HUGE windscreen on the front of my scooter. I will be OK no matter the temps here in Georgia as long as there is no chance of ice.
I have a triple layer armoured jacket and a big screen on my DT and that keeps the worst of the weather off. For the legs, I have a leg cover / apron thing or, if it's really hoofing it down, I keep a pair of waterproof trousers under the seat. Generally though, I find if I tuck everything in, I can stay mostly dry for the bulk of my short winter journeys - as long as I keep moving!
With regard to ice. Yes we have some now and again. The council gritters are pretty good at treating the roads overnight but I always check the temperature in the morning before leaving. Above zero and I go. Below and I take the car.