SOUTH KOREAN PRESIDENT Roh Tae-woo returned home Monday from a historic four-day visit to the Soviet Union, saying he and Soviet leader Mikhail Gorbachev agreed to work together for peaceful reunification of South and North Korea . . . TWENTY-FIVE PEOPLE were rescued after the ice they were fishing on broke free and drifted more than half a mile into a lake, Lake Mille Lacs, Minn., authorities say. No one was injured Sunday, but 10 ice houses and three all-terrain vehicles were left on the 5-inch-thick ice. Authorities said they would be recovered after the ice freezes back together, probably in about two weeks.