but then the line "how could she say to me love will find a way?" seems out of place, no? :-/
Not really, to me. Obviously John's switched to "he" to "she" to make it sound like a more conventional love song. But if you pretend that this is a song about Brian, this line could refer to any one of Brian's friends or a lover telling him not to give up hope; that love will eventually find him. I think it's a very sweet sentiment. This is one of the Beatles songs that I play the most. It's got brilliant words and the guitar part is really fun to play.
What book was your reference in, Flaming Pie in the Sky? I mean, there are Beatles authors and then there are Beatles exploiters, and the shelves are full of them. Even so, the quote doesn't sound particularly suggestive to me.
The opening of the song with John's feelings was a first for him and it became more common in his songs after this.
All this is saying is that John opened the song with a personal emotion. "...head in hand, turn my back to the wall" absolutely shows the singer's depression and possibly despair. It's an elegant way of summarizing a crisis of the heart. I love John's songs that explore this; John had led a troubled life, and this type of emotion ran very strong for him. Thank you, Bob Dylan, for (by example) showing John that he could turn some of his personal emotions into a really terrific song.
I suppose I should add that I don't see a song or a story as autobiographical, unless the writer tells me that it is meant to be taken that way. I think most creative people take the germ of an idea as their inspiration, and then flesh out the song or story as part of their craft. That way you get emotions that ring true, while not unduly burdening yourself with what might be happening in your own life. Even a pop star is going to want to retain some of his privacy! Cheers.