Can't speak to 2-4, but on 1., there seems to be research suggesting early epidemic growth can actually be quadratic: https://www.ncbi.nlm.nih.gov/pubmed/272668

Can't speak to 2-4, but on 1., there seems to be research suggesting early epidemic growth can actually be quadratic: https://www.ncbi.nlm.nih.gov/pubmed/27266847 https://www.ncbi.nlm.nih.gov/pubmed/27266847 Specifically, it notes that "Sub-exponential growth profiles may result from heterogeneity in contact structures or risk groups, reactive behavior changes, or the early onset of interventions strategies, and consideration of "deceleration parameters" may be useful to refine existing mathematical transmission models and improve disease forecasts." Not sure if there are more striking examples of "reactionary behavior change" than a massive lockdown.