From the directions on Pitt’s website – which is the only one of my kid’s list that requires it – you have to create a separate STARS account using the same login info that you do on Common App. And then, I think you have to manually input the classes rather than uploading a transcript.
Our college advising dept advised us that they have an easier way to do it on the back end, so my D26 was told to sit tight and save herself the hour of manually typing all that in.
(We are waiting for national merit to release anyway, which won’t be for another three weeks at least. So hoping the STARS thing happens, and the last rec letter that D26 requested will show up shortly. She is supposedly working on the Georgia Tech supplement today, which is her earliest deadline.)
I don’t know the answer to your question about the common app essay – I think you are asked with each application if you want to submit the essay, so if you select “no” then it just doesn’t include it? And surely this is independent of whether an essay actually exists in that space? But I’m really not sure.