Good advice here already! Consider lobster claw mittens for dexterity in very cold weather (or the bar mitts). I like the ventilation of my regular bike helmet even in extreme cold, wear it with a thin balaclava and throw up the shell jacket hood if it is windy. Light shell pants are a good layer in many conditions. I've been wearing Lake winter spd boots - spendy, but they are warm, light and efficient.