When having the exterior of a house painted, should all the caulking around the windows be redone?

How does that work? Do they pull all the old caulk out, and redo it from scratch?

Or, do they just look for where it might be drying out and cracking and add some caulk?

If there has not been any leaks can you just put on a fresh coat of paint?

Another question I have about exterior paint is should I get two coats, or if I am painting the same colors can I just do one?

The house has not been painted in 8 years.