Creep. The inner leaves of a folded section wrap the outer ones and stick out past them, so they are shifted back towards the fold by this much per sheet. Ordinary 80 gsm stock is about 0.3 pt. Leave at zero for anything not folded.
Pages are carried as form objects and placed with a matrix — the marks on a page are never interpreted, so they cannot be altered. Resources are copied byte for byte with their compression intact. Encrypted files are refused rather than half-read. Nothing is uploaded. Fold a proof before committing a run.