Unless you like textured walls, don't paint over dust. Wash the walls with trisodium phosphate (TSP) or a mild cleaner, like Jasco's TSP No-Rinse Substitute. For smoke-stained walls, Toto uses a 50/50 solution of bleach and water. To clean a wall, use two buckets. Load up your rag or sponge from your cleaning-solution bucket, and scrub. Before redipping, rinse the sponge in a second bucket filled with clean water.
In some cases, professional painters may include additional charges for specialized equipment that homeowners can't purchase on their own. Because professionals have licenses and access to such equipment, it's simpler to let them get those themselves. But providing some of the smaller equipment and extras directly really can help to cut down on the total cost of your project.
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.