All winter long. 23c's last winter, 25 in the back, 23 up front now. I really don't feel much of a difference. Skids are easier though, seated even.

All I do is use a fender.

I have some 28c Vittoria Randonneurs that I might put on the daily rider bur probably not.

Both my bikes either have a hole drilled or in the case of the Colnago, the BB shell has a clover cutout. I won't be riding the Colnago in bad weather though so that's moot. But the hole allows the Soma to air out and let any moisture escape.

Frame saver is good for the tubes if your frame is steel. My Soma has that. Marcus at Yojimbo's sells it.

BB's are easier to deal with if they're sealed, but this year my Sugino 75's have their matching unsealed Sugino 75 BB but that comes with an accordion like plastic sleeve to protect the spindle so I'm not too concerned.

Wipe your bike down as much as you can after a ride outside, the salt and the wet can beat up a frame some.