Have evidence of John Cabot's expedition ever been found in Canada?

Answer 1

Assuming you're refering to the failed 1498 voyage from which only one ship returned out of five (Cabot and the rest disappeared), and not the successful 1497 voyage, the answer is "no." No evidence of the 2nd voyage has ever been uncovered. The relative success of the first voyage is attested to by John Day in a letter to Christopher Columbus in that year. Perhaps in 1497 they got a little too far south and ran into a hurricane or even the Spaniards...