Well, Odoacer did not destroyed imperial title. Technically, Western imperial was never destroyed but merged back in to one with Eastern one. One of the reasons Byzantines protested coronation of Charlemagne was that from Constantinople point of view in was usurpation. So thats kinda answer your third question- there was no broken line as such to restore (albeit Zeno suggested that Odoacer should take Julius Nepo back to Rome as emperor, but Odoacer decided to pass on that). Was he actually responsible for another Emperor not being appointed after the deposition of Romulus? Officially,sending of imperial insignia to Zeno was initiate by Senate in Rome, but Odoacer was the one pulling strings behind scene. Did either Odoacer or Zeno have ambitions for a restoration of the Empire in the west, either under one or two Emperors? Constantinople had this ambition for centuries to come- thats why they cringed to they claims on Italy so much. Odoacer, formally was always a vassal of Zeno and ruled Italy in his name, but his main goal was to secure rule of Italy from Byzantine reach- that's why he acted trouth Senate- he tried to restore Senates authority in order to diminish emperor's.

Destruction of Western Empire is rather a modern convention. At that time it was just one more episode in long story of power struggle within empire.