They have to be Yes/No questions though. The DM can choose to clarify the answer beyond just a "Yes" if it's not clear enough, but the questions themselves 100% have to be Yes/No according to RAW.
I was more looking for generally useful Yes/No questions. Especially since you have 3 questions total, and casting it for a specific reason might get you the answer you're looking for right on question #1, leaving 2 others for "freebies".
Any good ideas? How about interesting questions instead of just useful ones?