7. "Does God really have power of things? - If so, then why does He let people become sick, oppressed and die?"
Allah has created all that we call the universe as a test for us. This is not our final destination. What we might consider to be "bad" or "good" could actually be quite the opposite. As regards oppression, this is something that Allah forbids for Himself to do to anyone and He hates it when anyone oppresses someone else. He does have absolute power over everything. He allows sickness, disease, death and even oppression so that we can all be tested in what we do.