Re #1, I think your argument is a nice intuition pump to motivate Many Worlds (MW), but I don't think it engages seriously with the main alternative interpretations (which was the biggest problem in the Eliezer sequence). When you say "Quantum physics says everything is a wave" you are almost on MW already: you have excluded by fiat epistemic interpretations of the wave function, as well as Bohmian interpretations, hidden retrocausal variables, etc.