McAdams's site is incredibly good. If you have the time and patience, you might also want to check out Vince Bugliosi's book, Reclaiming History. As far as I'm concerned, his credibility and research are impeccable.
One thing I've never understood is hiring a shooter, a shooter to kill the president, no less, who can't hit the broad side of barn. Have you been to Dealy Plaza? I have. The grassy knoll can't be much more than 40 yards away from where the president was sitting. I'm not an experienced gunman, but a couple hours of Duck Hunt would prepare me enough to at least hit a body. Did you notice that crack, not hole, is closer to the driver's side? Were they aiming for Jackie, too, or the driver (not that they'd need to hit the driver since the limo was essentially a stationary target)? Have you noticed that all the blood, brain, skull fragments and bullet fragments were all found to the front of the president's body as would be consistent with a bullet coming from the rear?
It's not even a close call. Those bullets came from the rear.
ETA: 2nd paragraph addressed to roundhead