The only thing I think you got wrong was the phase shift question. It looks like you overlooked the - sign.

\-1/3 cos(pi\*x-1) = 1/3 cos(pi\*x - 1+pi)), so the phase shift isn't 1/pi

..although it looks like it's actually complaining about the period? You said 2, 2 is correct, and it's hard to believe you didn't "simplify" that properly.