Re: Washington's lack of usage in the US
I think it just feels old fashioned. The -ington ending isn't nearly as popular in the US as it has been in Brazil, and the names with that ending that do sound current have connections to pop culture or shorten to trendier nicknames (Remington, Kensington, Lexington, Wellington, Ellington, Carrington, Arlington, Barrington). Washington shortens to Wash, which would feel like a very strange nickname in contemporary English. And George Washington is not a hugely popular figure.