Does everything have to be submitted before deadline? including LORss, Essays?
Common Application and Writing Supplement (if applicable) should be submitted before the deadline.
They are more lenient with LOR’s, transcripts, and other stuff that is not submitted directly by you, since they know that they are out of your hands, and they WOULDN’T hold those being submitted late against you.
However, it is always better to check with your teachers and counselors to submit them as early as possible, since not submitting them delays the evaluation of your app.