screw shoes are good if it's icy at all, they're not an impediment in normal snow conditions, and can still be manageable on clear, dry pavement for short stretches. (google "screw shoes" and you'll be taken to matt carpenter's instructions.) generally, though, i do my snow running (and i do a lot of it in season) in whatever i'm otherwise running in -- in recent years that has meant new balance 790s or 100s.
as for clothes, wear layers conducive to the weather. odds are you'll go through warm and cold patches, especially if it's windy, so having a windbreaker or whatever around your waist might come in handy. depending on the temperature and how much snow gets kicked up, you might be happiest in tights -- and gaiters.
to prepare, make sure you put in some hours ahead of time on the likely surfaces, and remember that running in snow is much slower than on normal dirt, so be ready to be out there a while.