If I don’t match to a college and move on to regular decision, then can I alter my common app info (test scores, essay, etc.)?
The common app closes you out after you submit to a school (you can always change it BETWEEN schools though). If the university is willing to let you, email them and coordinate it that way. I don’t think they can reopen the actual common app for you. Someone can correct me if I am wrong. Test scores can always be sent every time you take one, so that alternation should be easy enough.