#1 No, I don't think that's true. If carried, varied, etc. sounded like "it" or even "id", it would sound more like a South African accent than a British one.

The biggest difference between British and American pronunciation, in my opinion, is in the way we pronounce "r"s, especially in words like library, dictionary and secretary. These words also contain one syllable more or less in American vs. British English depending on your point of view.

The pronunciation of "a" is another strong indicator of whether a person is English or American.

Hope this helps!