1) The lecture discusses common fallacies of relevance, including genetic fallacy, ad hominem, ad populum, appeal to pity/force, and straw man arguments. 2) Genetic fallacy involves attacking the origin or source of an argument rather than the argument itself. Ad hominem involves attacking the person making the argument instead of the argument. 3) Appeal to popularity (ad populum) involves citing something's popularity as a basis for its quality or correctness, while straw man involves misrepresenting someone's argument to make it easier to refute.