I didn't get as far as Heinlein's introduction to the story. The last point you mention could be easily checkable in a copy of the Parsons biography, which I've read but don't have. (Or in Bill Patterson's Heinlein biography, which I've also read and also don't have.)

What I didn't mention in the post is that I'd already been dismayed by the scene in which a German agent, about to be secretly landed in the US from a sub, gives an expository lump in the form of telling the sub officers his entire life story.