Questions on Determinism and Compatibilism

1. What distinguishes hard determinism, compatibilism, and indeterminism/libertarianism?
2. Why shouldn't our belief that we can improve ourselves and take responsibility for actions prove that Holbach's determinism is wrong?
3. How do compatibilists use the distinction between internal and external constraints to defend free choices?
4. How could libertarians respond to compatibilists by distinguishing between causes of and reasons for our actions?
5. How is the belief that free actions are based only on "unimpeded rational desires" supposed to be an improvement on compatibilism?