Decision Theory: Self-locating Belief, Anthropic Reasoning, and Skepticism

Is there a distinctive type of "self-locating" uncertainty which concerns who one is or what time it is (as opposed to what the world is objectively like)? If so, how should such uncertainty be represented? How should one update one's self-locating probabilities based on new evidence? Should an "anthropic principle" or "observation selection effect" influence our evaluation of cosmological theories? Is the apparent fine-tuned nature of the physical constants evidence for multiple universes? For the existence of God? Does a principle of indifference show that you should you think you are a randomly formed "Boltzmann brain"?