Ghayra annī creates an adversative transition, with the first-person suffix serving as the noun of anna. The imperfect in qad astaʿīnu can describe a recurrent or present practice.
Idhā khaffa bi-l-thawī al-najāʾu is a temporal construction; al-najāʾu is the subject of khaffa. The deferred bi-zafūfin identifies the actual means of countering distress: the swift mount.