I've become mainly a commuter since turning 50 twelve years ago, and I usually take the layered approach.
Magicshine headlamp and double MS taillights set on alternate blink have erased any fear of motorists not seeing me.
I haven't yet crossed over to studded tires because both bikes are still 27" and I haven't bothered to convert either to 700c.
My asthma forces me to cover my nose and mouth with a scarf - and I find that exhaling through my mouth and inhaling through my nose completely keeps the asthma at bay - primarily because of the moisture I recycle as I breathe in.
When it's really cold, my eyes start streaming tears - I may try ski goggles to see if they help with that.
When conditions begin to get mushy or slick, I'm on the bus. No need to be a martyr just yet.