Which source of law takes precedent (priority) in the following situations and why?

1. A federal statute conflicts with the U.S. Constitution.
2. A federal statute conflicts with a state constitutional provision.
3. A state constitutional amendment conflicts with the U.S. Constitution.

Following questions.

1. Explain the difference between a concurring opinion ad a majority opinion.
2. Outline the difference between a concurring opinion and a dissenting opinion.
3. Why would a judge or justice write a concurring or dissenting opinion, given that these opinions will not affect the outcome of the case at hand, which has been decided by the majority vote.