Short answers, pulled from the story.
Protector of the Confederation of the Rhine was the title held by Napoleon, Emperor of the French, in his role as leader of the Confederation of the Rhine from 1806 to 1813. The title was created by the Treaty of the Confederation of the Rhine, an international agreement between Napoleon and certain German princes.
The founding treaty named Napoleon Protector and gave him one explicit power: the right to appoint the successor of the prince-primate after every departure. The treaty did not define further duties, did not commit him to guaranteeing member states' territorial integrity, and gave France alone the authority to decide when to mobilise the Confederation's military forces under Article 36.
The prince-primate was the chair of the Federal Assembly, the intended deliberative convention of the Confederation's member states. Napoleon's role as Protector gave him the sole right to appoint successors to this position. The Federal Assembly itself was never realised in practice.
The Confederation of the Rhine existed from 1806 to 1813, with Napoleon serving as its Protector throughout that period.
Yes. In 1810 and 1811, the member states of Westphalia and Berg ceded territory to France. Because France was not a member of the Confederation, those transfers violated Article 8 of the treaty, which required member states to cede sovereignty only to other Rhenish states.
The title appeared in both French and German. In French it was Protecteur de la Confédération; in German it was Protector des rheinischen Bundes.