Creative Speculation

So that's the first problem is that your list contains a lot of imaginary "facts" such as:

• CE399 was planted
  
• There were more grains of bullet in Connally's body than missing from CE399
  
• Oswald was not on the sixth floor when the shooting happened...
  
• ... and the Warren Commission knew it had witnesses proving it and suppressed that information.
  

Since the truth of a deductive argument depends only on the soundness of the premises and the validity of the logical inference, any arguments that proceed from the above "facts" are not sound, so there's nothing to be gained by examining them for logical validity.

As for the validity of arguments where the premises are at least plausible if not proven, the other problem is that conspiracists as a group strongly favor inductive reasoning over deductive (for reasons that are pretty danged obvious). The problem with inductive reasoning, which conspiracists seem to be blissfully unaware of, is that it's deductively "invalid" in the sense that the conclusion could be false even if the premises are true. Not only can they be wrong, but they frequently are. With inductive reasoning, instead of questioning the logical validity (since there is none), the question is if the argument is "convincing" or "probably true," which is a highly subjective question. Since a conclusion of conspiracy seems to be their starting point, there's nothing remarkable about the fact that conspiracists can convince themselves (if not even other conspiracists) that there speculations are "probably true" (and then in short order promote them to be "definitely true" just because that sounds better). Of course, if they could find sound, fact-based and logically valid deductive reasons for believing that there was a conspiracy, then it wouldn't really matter where they started. But they simply haven't, and dubious "facts" and weak inductive arguments are not an acceptable substitute.

The situation here is not symmetric: The case against Oswald IS the "official story" because it's the one best supported by the actual evidence. If you want to claim it isn't true, then the burden of proof is on you, and offering speculations as facts doesn't do the trick, nor will dubious inductive arguments. Simply claiming that all the evidence we have must be fake won't do it, either, if you can't prove it. Since human perception and human memory are both fallible, pitting witnesses against each other and deciding who is right or telling the truth based solely on the story they tell, rather than correlating with the physical and documentary evidence, doesn't do the trick. And accusing people of participating in a cover-up simply because you don't like the story they tell or because they reached different conclusions after their own examination of the facts will certainly not turn things in your favor.

After 50 years, it's still the same issue: Can you or can you not make a case that at least resembles evidence-based reasoning? "Rhetorical device," indeed.