1) FDR was paralyzed from the waist down and couldn't walk. He used a wheelchair. I would recommend looking this up to find some personal reasons as to why this is interesting. I however find it interesting because we still aren't quite sure if the cause of his paralysis was polio or Guillen-barre's syndrome.
2) FDR was the only president to serve for 4 terms. Again I recommend looking this up to find something you find interesting. I however just think it is interesting because during the time he was president (the Great Depression and beginning of WW2) the United States was pretty unstable, which shows the trust that the people had in their president at the time.
Answer:These grassy areas were known as downs. Later, after real tracks were constructed (usually on the same sites) they named the track and kept the downs in the name. Probably the most famous track there was Epsom Downs which originated around 1661 and became famous for the big race they started known as “The Derby