UBS AG Is Listed as an ADR on the New $107 \quad1/ 2 - 108\quad3 / 8$

UBS AG is listed as an ADR on the New York Stock Exchange (NYSE) in dollars (USD). It is also listed in Zurich in Swiss francs (CHF). Here are some quotes:
NYSE (in $) $107 \quad1/ 2 - 108\quad3 / 8$
Zurich (in CHF) 187-188
CHF/$ (Swiss francs per dollar) 1.7360-1.7380
In addition, you have to pay a commission of 0.3% in New York or 0.5% in Zurich.
a. Where should you buy UBS shares if you are an American investor?
b. Where should you sell UBS shares if you are an American investor?
c. If all commissions were waived for a large transaction, would your answer be the same?
d. Answer the same questions for a Swiss investor.