Incl. Criteria 8 (Cough that is attributed to IPF, which has not responded to anti-tussive treatment, and which has been present for at least 8 weeks prior to Screening) – does this rule out patients that have not had anti-tussive treatment at all?

No, there is no requirement for prior anti-tussive therapy although most patients will probably have tried something. The wording “which has not responded to anti-tussive treatment” is intended  to make sure that patients who have easily controlled cough don’t stop taking effective meds just so they can be enrolled.