<< The treatment Bradbury handed in was intentionally crap, based on what he thought the producer wanted-- and that's THE ATOMIC MONSTER/GROUND ZERO. Right? <<

Right.

<< Then he gets notes, and does a polish of that. Yes? <<

There are three versions of the crap treatment, but they're almost identical to each other and I think they're all dated within a few days of each other.

<< (Is it essentially the same story? Is it what Alland describes, above?) <<

It's pretty much what Alland describes, but toward the end there's dopey action (a Xenomorph version of the sheriff runs across throwing sticks of dynamite, etc.), and it wraps up with the spaceship completely buried, and Putnam having the attitude of "Well, they've got lots of air and food down there. Maybe in a few years we can dig 'em up and see how they're doin'."

<< And then he hands in IT CAME FROM OUTER SPACE and everybody loves it, adopts it as their own, etc., etc. And they hire Harry Essex to trim it down and put it into a workable shooting script format. <<

You got it.

Both the crap one and IT CAME FROM O.S. have all the same characters, the same everything; the crap one doesn't fall apart and become crap 'til the end.