Yes. It's an extremely Heinlein choice; he's regarded by the sympathetic as having been highly patriotic, by the unsympathetic as virulently nationalistic.

I never thought of Heinlein as especially patriotic or nationalistic; he was, on the other hand, a big fan of revolutions against oppressive regimes.

And he had some... interesting... ideas about who makes a good sexual partners. [1]

1; https://www.amazon.com/dp/0441748600

I think it's a mistake to view “explored in fiction” with “endorsed”.

Full disclosure: I never bothered to read anything of his written after "The Moon is a Harsh Mistress", since the universal consensus seems to be that his later books are very, very strange.

He had a blocked carotid artery for several years, and I some Heinlein fans blame his crazier stuff on that.

I think his later books are just what happens to many successful creatives. They get so famous that no one else has any editorial control over what they produce, and the quality of their work decreases.

See also: https://en.wikipedia.org/wiki/Westermarck_effect

That is correct, 1776 is the year the US signed the Declaration of Independence, and is considered the year the USA was created.

Yeah!