A question about filling out my application

I attended a different high school for only two months in my 9th grade year and left quickly with only a few grades in. Should I mention that I attended that school?

Also, do I have to complete the entire part of a section or until there is a green check beside it. The application is asking about what classes I’ll finish before I attend. But I got a green check on this certain section.

Also, if my school only needs one ACT score, but I took the SAT before, do I just say ‘No’ to whether I took the SAT or not?

On the common app, it asks you to list all your schools attended. Your transcript will list this too. It would be strange for your app and your transcript to not match.