“Downton Abbey” hunk Dan Stevens is in New York making his Broadway debut, but we hear he’s spending downtime helping victims of Superstorm Sandy. The star of “The Heiress” volunteered last weekend in Red Hook, we hear, and also hosted four displaced downtown pals at his temporary Upper West Side digs. The civic-minded Brit — who plays debonair Matthew Crawley on “Downton” — even encouraged Americans to vote on Election Day, posting on Twitter (in an unverified account), “I can’t vote, but maybe you can? Locate your nearest polling station and #vote!” In a UK column he wrote about Sandy, Stevens said of Britain, “In Hertford, Hereford and Hampshire hurricanes hardly ever happen.”