Not only careful communication is essential, but we would greatly recommend, when you pick out your type and brand of paint that you go and pay for it, with the contractor's discount, which is given by Sherwin-Williams and most paint companies. Then you will know how much paint you purchased and the coverage. If it is possible, inspect the work of the painter daily.
I am in northern Nevada and you have not yet gotten sufficient responses to provide a painting cost chart showing the averages. I do have a quote from an outside (Not Homeadvisor referral) painter who is local for $2,750 for soffits, patio cover and posts, Garage facia (redwood clapboard above (~300 ? Sq. Ft.) on a 2046 Sq. Ft. home where the walls are 9 ft tall and it is fully stuccoed with plastic stucco surfaces, so not being painted.