1. Are human rights Invented? (course reading: Inventing Human Rights, by Lynn Hunt)
Yes, of course. Man didn't start on Earth with any kind of rights, we meandered around killing **** to survive (including each other) then determined that "Whoa hey, you shouldn't do that."
2. Are human rights the same as political rights? Or is one a subset of the other (or are they independent)?
Eh, perhaps I don't quite grasp the question. I would think human rights are ingrained in political rights (or vice-versa?), but it isn't if you're looking worldwide. Our system of political rights differs greatly than say North Korea.
3. If invented, who decides what human rights are? (Corollary: if discovered, who decides what human rights are?)
The Government. In America your rights can change based on societal change, such as interracial marriage, or gay marriage, but it takes Government (or judicial) action to change things. We don't use polling measures to change things, we elect people to the Government in the hopes that they change things.
But again, if you look at North Korea/China/Middle East etc, society doesn't have a say, because those Governments aren't changing.