1) In order to remove this evil spirit from the hands, one must wash each hand three times alternately. According to the Gr”a, one must wash four times, the fourth time being to remove the defiled water which now rests on the hands. (Shulchan Aruch and Mishne Berura 4)
2) One should wash the hands even of small children, as they touch food. A non-Jew, however, who touches the food does not defile it, as he cannot become impure. (Mishne Berura ibid)