Error and Doubt in Exam

I think i  found an error in a question on the exam; when asking about the sample size for a one-tailed hypothesis test, the formula for a two-tailed test is used
it should use z(1−α) instead z(1-α/2).

My doubt about exam question is in question  2

If we are interested in revenue, and revenue depends solely on the number of ads that are viewed, I believe that user retention does not affect it. It doesn't matter whether an ad is viewed by User A, who has been a user for 30 days, or by User V, who is new.

Thanks in advance!