* Grain markets hesitant before USDA data at 1700 GMT * USDA widely expected to hike U.S. corn crop, stocks * Corn touches new three-year low (Updates with U.S. trading, adds new analyst quote, byline, dateline, pvs PARIS/SYDNEY) By Mark Weinraub CHICAGO, Nov 8 (Reuters) - U.S. corn and wheat futures slipped while soybean futures