Hello, Anon, here's my opinion as to the first question: I wouldn't say "my head pains". You can say "it pains me to see your sorrow". "My head hurts" is also OK in some contexts, for example, you've been in a car crash, and a doctor asks you how you're feeling, then you can say "my head hurts" (you've banged it, or whatever) The headache is inside your head, but your head hurts because of an external reason.
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