One would hope that nowadays the Secret Service would keep better track of the whereabouts of people known by the CIA and the FBI to have had dealings with foreign governments considered to be enemies of the United States.

Also, of course, it is no longer possible to buy a Mannlicher-Carcano rifle with a hunting scope on it by simply sending away for it in the mail using a phony name on a postal money order.

I think it wouldn't differ. Remember the guy shot him from a building through a window. Sure security now is tighter but I don't think anything would have changed

instead of one guy with a 8 mm movie camera , there would be dozens of cell phone pictures .

instead of oswald theyed set up carrot top

Ozwald would have been killed by a drone