"is" or "will be" required to do something

1) You are required to take care of my cat after I go out of town tomorrow.

2) You'll be required to take care of my cat after I go out of town tomorrow.

3) He was advised that he was required to sometimes work long hours.

4) He was advised that he would be required to sometimes work long hours.

Q1) Are they all correct? If so, what is the difference between 1) and 2), 3) and 4)?