I never heard that he made it to Cuba.
A person identifying himself as Lee Harvey Oswald tried to get a Cuba visa in Mexico City, but was turned away at the Cuban Embassy. There is some doubt that this person was actually Oswald, as I understand it.
As to the the Walker assassination, it’s strange, and I can’t explain it. I just don’t know what it means, other than that Oswald was a hard-core communist. Maybe he was.
See also my post #43 a little farther down concerning where JFK's assassin could have fired from.