David, re the time of the changes -
Off the top of my head, I can come within a year or two of the changes:
#7 was the first - Byron Nelson drove the green in one of the early Masters (I think it was 1937), and the green was moved back and bunkered.
#10 green was moved by Perry Maxwell (who also did #7), in 1938 - one complaint was that the original green had drainage problems, so Maxwell moved the green 70 yards back to a ridge.
#16 was redone by RT Jones Sr in 1948
the #11 tee was moved back by the new #10 green in the early 50's (1951?)
the "Hogan bunker" was added to #15 in the mid/late 50's
I'm not sure when the bunkers were added to #17, or taken out of #18.
Tom -
I pieced together the course from a lot of different sources. David Owen's and Frank Christian's books were important for their photos, Geoff's "Golden Age" book had some old photos, Mackenzie's sketches and descriptions of the holes in the first Masters tournament program, the original green plan for the 10'th hole, Charles Price's book on the Bobby Jones and the Masters, plus reading snipets from golfer bios that mentioned the Masters tournament in its early years.
Re the 15'th hole -
The shape of the water hazard has evolved some through the years. Some of Mackenzie's original drawings of the course show it is a stream which cuts across the 15'th, 17'th, 7'th and 2'nd holes. The photo of the hole in Owen's book shows the hazard shaped a little more squarely than its current shape, but my decision was driven most by Mackenzie's description of the hole printed in the first Masters tournament program, "A pond in front of the green provides the penalty for the long player who fails to make a perfect second shot." It's for that reason I chose to represent the hazard more as a pond than as a creek.
Dan Kelly -
I'm not sure on the evolution of the bunker style, but I can make a guess. If you look at pictures from Masters tournaments in the 1940's/1950's, the bunkers at Augusta National had "fringes" - for about a foot's width around the bunkers, the grass was grown 5 or 6 inches high. My guess is that as the course got pretty for TV in the late 50's/early 60's and eliminated the rough and greened up the place, it was deemed that the fringes didn't belong, but that the sharp edges on the bunkers would keep some of the 3-d appearence that the longer grass produced. Maybe someone else has more specific details.