Short answers, pulled from the story.
The Congress of Erfurt was a diplomatic meeting between Napoleon, Emperor of the French, and Alexander I, Emperor of All Russia, held from Tuesday the 27th of September to Friday the 14th of October 1808. Its purpose was to reaffirm the alliance created by the Treaties of Tilsit in 1807, following the end of the War of the Fourth Coalition.
The Congress of Erfurt produced the Erfurt Convention, a document in fourteen articles. It called on Britain to cease its war against France, recognized Russia's conquest of Finland from Sweden, and committed Russia to aiding France "to the best of its ability" if war broke out with Austria.
Charles Maurice de Talleyrand-Périgord secretly advised Alexander I to resist Napoleon's demands during the congress, working against Napoleon's interests while nominally serving as part of the French diplomatic effort. Talleyrand had concluded that Napoleon was leading France toward destruction.
The congress drew kings, princes, dukes, barons, and notables from across Europe. The actor Talma and the entire Comédie-Française attended, performing sixteen French tragedies. Goethe was courted by Napoleon himself, and the twenty-year-old Arthur Schopenhauer arrived in Goethe's entourage.
Russia largely failed to honor the Erfurt Convention. When war with Austria broke out six months after the congress, Alexander aided France as little as possible. By 1810 both emperors were considering war with one another, and by 1812 Russia had stopped complying with Napoleon's Continental System entirely.
Yes. Erfurt in October 1808 was the last meeting between the two emperors. Their relationship deteriorated in subsequent years, culminating in Napoleon's invasion of Russia in 1812.