For the question of personal identity, another essay, that was posted on Less Wrong by Eliezer, is here:

http://lesswrong.com/lw/19d/the_anthropic_trilemma/

However, while this essay presents the issue, it admittedly does not solve it, and expresses doubt that it would be solved in this forum. The solution exists in philosophy, though. For example, in the first essay I linked to, in Daniel Kolak's work "I Am You: The Metaphysical Foundations for Global Ethics", or also, in a partial form, in Derek Parfit's work "Reasons and Persons".