That's two questions. :)
1. To my knowledge, just the one.
2. If it was a conspiracy, one could reasonably speculate that Dallas was chosen because that's where the planned patsy lived. Also, the setup was good, probably better than Washington D.C. because it was a new location not well known to the Secret Service and thus a place where Kennedy didn't have his usual level of protection.
I'm sure that Lee Harvey Oswald shot Kennedy that day; it's just that I'm not sure he was the ONLY one who shot Kennedy that day.
The first shot hit him in the neck area and he grabbed his neck and was having trouble breathing and he leaned way over forward. The second shot apparently missed. But look at the third shot, and second hit on film. He's bent way over and then he jerks backward violently and part of his head was violently blown to the rear. I don't think there's any doubt about that whatsoever, Now, there's only two ways that could make him jerk back violently. One is a shot from the front, which would have to be from a second shooter. The other is that a bullet from the rear hit his brain and caused his muscles to involuntarily jerk him backward violently. Try this yourself: sit in a chair and lean way forward. Now jerk yourself back as hard as you can. You'll have trouble jerking yourself backward as violently as Kennedy jerked backward.
And then a question for you: Why did Jack Ruby feel so compelled to kill Oswald? It's always bothered me.
Unfortunately, the feds botched things up when they took the body back to D.C. and let a couple of amateurs perform the autopsy instead of leaving it for professional pathologists and murder investigators in Dallas.
2 other known plots (In Chicago and Tampa) to kill JFK in the weeks just prior to Dallas were broken up. No. 3, the Dallas attempt, was successful.