If you are in the room, you might be able to make the shots - although the FBI failed to, and Oswald was a lousy shot - but my main problem is that he could not have moved through the building as needed without being seen by some people, and not by others who did.
The photos of Kennedy do not show a small wound in the back of the head. They are distressing for a number of reasons, not least they clearly show the back of the head has exploded out.