The inflatable clown used by Kevin to impersonate his father in order to frighten Hector is a nod to Pennywise the Clown, a form of the titular antagonist of the Stephen King novel, It. The character was previously played by Tim Curry in the 1990 TV miniseries adoption of the novel.
I think it is the first one (shoppers find sushi...). Cultural diffusion refers to the spread of different cultures around the world. Finding Asian food in America definitely shows an example of cultural spread.
