I live in Salem but I keep my boat in Maine so I've never sailed here and can't tell you much. I don't think there will be much, if any, ice in the harbor. Pretty sure I've seen some boats in the water at one of the marinas at Pickering Wharf. There is a water taxi service that provides moorings and transport to and from your boat:
Salem Water Taxi | Seasonal Mooring Rentals & Launch Service
The only other thing I know about the harbor is that it's crowded.