Why does the Torah deal with secretions of a person’s body? What is the Torah’s approach towards death? And what is the meaning behind the halachot of purity and impurity?

It is well-assumed that one should not invade another person’s privacy, however does this obligation exist even after death? Is it permitted to publish writings and personal correspondence postmortem? Does halacha have anything to say on the matter?

A kidney donation can undoubtably save a life. However, considering there is a level of risk associated with donating a kidney, should people be encouraged to undergo this process? If there is a risk, even if it is a low one, is it even permitted to donate a kidney to someone else?