Answer to Question 1
Using the fact that the noon solstice Sun was directly overhead at Syene, on the Tropic of Cancer, yet was 7 degrees south of his zenith in Alexandria, Erastothenes realized this was due to the curvature of the Earth, and that the 7 degrees was about 1/50th of the Earth's total circumference, so the Earth must be about fifty times larger in circumference than the 800 kilometer separation between Alexandria and Syene, or about 40,000 kilometers around.
Answer to Question 2
FALSE