Ok, I’ll have a go at this:

1 - I can’t answer this unless you explain what “identify as a man” means. I don’t believe in gender stereotypes, so to me “man” means “adult human male” and nothing more. It doesn’t mean a masculine person or a person who likes cars or any other “male” stereotype. Personally I don’t “identify as” anything. I am the sex I am, that’s just a fact that says nothing about my personality, likes/dislikes, or intellect.

2 - Sex is OBSERVED at birth. Excluding intersex people (a tiny tiny minority) biological sex is an objective, observable fact.

3 - What is the “wrong body”? Do you think that if a woman is masculine, she’s “in the wrong body”? I don’t - I think it’s completely fine to be a butch woman, or a feminine man. Butch women are not less female than any other woman. A feminine man is no less of a man than any other.

4 - I have yet to see a definition of “gender identity” that doesn’t boil down to gender stereotypes. And I don’t believe that gender stereotypes are a good thing, I think they should be rejected. I am a woman because that is the sex that I am, not because I conform to feminine stereotypes. If I started conforming to male stereotypes like wearing men’s clothes and, I don’t know, fixing car engines (?) that wouldn’t make me a man.