Not in all of those instances. In the case I referred to about ex post facto laws, the purpose was to extend the prohibition against the states that Section 9 only imposes on the federal government.
The tenth amendment makes it clear that rights are reserved to the people. They are therefore off-limits to the states.
This is the tenth amendment, with emphasis provided by me: "The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people." It's purpose is only to restrict federal powers. It deliberately leaves open the question of where the dividing line is between the powers of the states and of the people.
No it doesn't. A state cannot assume powers reserved by the people.