Three observations:
(1) Apply Occam's Razor and see how much of this silliness evaporates.
(2) Most conspiracy theorists surmise that JFK was killed by the "military-industrial complex" or the mob or angry Cuban nationalists.
In reality, the Soviets had real motive to kill him and they definitely were in the business of clandestine assassination.
If one really did buy into the conspiracy mindset, the most logical culprit is the Kremlin.
(3) Most people would prefer to believe in a vast conspiracy than face the scary notion that one disturbed individual can change the course of history.
I'm no expert on the assasination.
I've been to Dealey Plaza a few times, visited the 6th Floor Museum and over the years, have read a number of books.
I can't tell you who ordered the assasination or why it was ordered - but one thing seems pretty sure to me.
There was more than one shooter in Dealey Plaza.
Looking at the various testimonies of those present and the Zapruder film, it certainly does seem as though there were multiple shooters.
How many? I'd say 3 or 4. Triangulated fire. Guaranteed to make sure that Kennedy didn't leave Dealey Plaza alive.
"Most people would prefer to believe in a vast conspiracy than face the scary notion that one disturbed individual can change the course of history."
It came within an ace of happening 3 years before:
http://toledoblade.com/apps/pbcs.dll/article?AID=/20031121/NEWS08/111210127