We use similar questions with the exception of #6 - our data sets are small enough that just getting a correct query is fine. We add a small relational design exercise to see if they understand data modeling 1-to-N and M-N relationships.

Totally curious - what is your fail rate like for applicants at the first stage for the window function? We are happy with more junior engineers who usually haven't used a window function but can currently do simple queries and an easy candidate to move forward with will come up with a group by subquery . . .

I'm guessing that 2/3 to 3/4 of our in-person interview candidates look (on paper) like they could handle simple queries and grouping but struggle in the interview context.