Hello, katrina
I've heard different reasons at the Fests for why James Hall (the first Willie) left the show; apparently, he was either an alcoholic, or he just wasn't right for the part. Personally, I'm not sure the other cast members really remember.
Willie Loomis is no relation to Mrs. Johnson in this series. I believe he was the housekeeper's nephew in the 1991 series.
ProfStokes