Corfu Town in winter is pretty much the same just less crowded than summer as several hotels stay open all winter and have heating. The resort area such as Agios Stefanos very much closes up with just a scattering of places open such as the middle supermarket which is open daily, 3W's bar and Town Pizza open. You would definately need accommodation & somewhere with heating and also I would suggest a car too. Village life such as Avliotes is much the same as summer with cafe's and a few tavernas open all winter. ATM's in resort do not work during winter months so your nearest place during off peak months would then be in Sidari. Various bars coffee shops supermarkets etc remain open all year round in Sidari and Acharavi. Acharavi would be your nearest bank as well if required.