So you are looking for a nice dinner by a beach not far from DL? Personally I like Newport Beach, but its more like 30 minutes. I'm not as familiar with Huntington Beach but i am sure there are ok places there and probably a little closer. Are you looking for social places to walk or more on the romantic side? Part of Newport Beach has like a "boardwalk" area with shops and restaurants and games/arcade etc, but as you get to corona del mar it gets quieter.
Swimming in November? I surf, but wear a full suit, kind of a chicken with cold water, but I see tourists swimming all year, never know where they are from.