U2 was a top secret project at the time Oswald was a Marine, and no one at Atsugi Naval Air Station was told of its true purpose. Oswald might have speculated that the strange-looking aircraft was a spy plane. He could have counted the number of U2 flights that took off and landed on his watch, and estimated their rate of climb and the method of descent. But he could not have known the U2s' destinations because his radar didn't have the range to track the planes crossing borders. Nor was there any radio communication between U2's and their bases, the better to keep the Soviets from tracking their flights. And, the Soviets already knew plenty about U2s because they had spotted them since July 1956, when they made their first overflights of the USSR. Note: Soviet authorities interviewed Oswald twice in his first week in Moscow--and ordered him to leave after his visa expired at the end of the week. Whatever he told them about the U2's he'd seen wasn't worth anything to them.

The $435.71 (not $1500) that the US Embassy in Moscow lent Oswald for his return trip was part of a State Department repatriation fund used by several thousand needy and/or politically high-profile US citizens stranded abroad, and was not granted until State ascertained that Oswald’s mother and brother could not or would not advance the money to him. (Oswald repaid the loan promptly.) And, Ruth Paine and others who helped Marina Oswald in Texas weren't linked to the CIA. Once Oswald returned to the US, his case was handed over to the FBI because the CIA officially had no authority to operate in the US. FBI agents interviewed Oswald twice (from cars parked outside his home) soon after he returned but took no further action. Oswald cooperated with them because he was afraid of being charged as a traitor.

Marcello certainly had motivation to hate the Kennedys because they deported him to Guatemala. But there is no proof that he actually set it up.