The US is not seeded. Germany and Brazil get autoseeds.
ESPN Article.
Home field advantage is enormous. US did MUCH better in '94 than anyone thought they would, in fact, the US was ranked in the 30's that year and probably would not have even qualified. Both Korea and Japan reached the knockout phase last year which was very surprising. And although France had the best player in the world in '98 (as they do today) HFA went a LONG way.