I did read somewhere why Ed didn't make the cut; as I recall, Chuck Yeager had insisted that if he came last in the class of 12 trainee test pilots, then the other 11 should all be accepted as well, but I think in the event none of them were? Glad he got up there in the end!
Bob Lawrence may well have joined NASA after the USAF MOL project was cancelled but sadly he was killed in an F-104 training accident at Edwards; many of his fellows became Astronauts on the Shuttle, Crippen, Overmyer, etc.