Year book committee

Joining a yearbook committee would look better, but not by much. I recommend choosing yearbook committee as long as study hall is not a super productive time for you. If it's an important part of your study habits, then continue doing it - a GPA boost will help your application more than yearbook committee. Hope this helps!

It depends. If this activity makes for a good match with your current set of co-curriculars, then yeah! Go for it. If you plan on adding it as "Activity #8" on Common App, though, you may be better off just not doing it, and investing your time into a more meaningful activity.

I would say yes since it shows colleges that you are following your interests and taking time to pursue those interests outside of class. Extracurriculars and clubs show colleges that you can efficiently manage your time while spending time doing what you like and doing well in school.

Joining any extra curricular activities will be beneficial to your college resume because it shows colleges you are applying to what other interests you have outside the classroom. Choose electives or after school activities that interest you and that you enjoy!