As we tarried (επιμενοντων ημων). Genitive absolute. Note επ (additional) with μενω as in Acts 12:16.

Many days (ημερας πλειους). More days (than we expected), accusative of time.

A certain prophet named Agabus (προφητης ονοματ Αγαβος). A prophet like the daughters of Philip, mentioned already in connection with the famine predicted by him (Acts 11:28), but apparently not a man of prominence like Barnabas, and so no allusion to that former prophecy.