Basically, what drove his transition was the desire to be loved, and in a way that he thought women were loved, at a time when homosexuality was still a taboo.
Absolutely. Informed and enchanted by Hollywood and stereotypes.
I had exactly the same impression of Michael. The give away on the A was him saying that he really desired sex with women but when it was clear that women didn't desire it with him, the answer was to be one. As you say, he also had a non-sexual trauma based need to be loved.
Interestingly, Orlando's freedom seems to have partially come from letting go of stereotypes, whereas it is hanging on to stereotypes that helps to keep Michael locked in the prison of his troubled thoughts. He was so clear that he could only be a man when he was a manly man. He looked sympathetic yet also somewhat appalled at Orlando's take on "manliness". I suspect that the wisdom to see compassion here has only come with age and self reflection - it looked like he was fighting his homophobic instinct on that. A younger man in his position, who recognised their own internal homophobia, probably wouldn't have felt the need to attempt to temper it. That said, they may do nominally, because it's expected to be supportive of gay people under the full LGBT umbrella.
Between the two of them, where they agreed and where they vehemently yet respectfully disagreed, they seem to represent a very clear picture of the vast majority of men who identify as women. There will be a small number who don't fit in to either of these broad categories, whose dysphoria has a different origin, but they are lost amongst the rest.