The companies with the best paint products are Benjamin Moore, Dunn Edwards, Sherwin Williams, and Vista Paint. As a painter I don't recommend Berh from Home Depot as much because it's quality is just marketing. Flat paint has no sheen and it shows its true color, but is not easy to wash or clean. Satin, eggshell have low sheen and is washable. Semigloss ang glossy has a high sheen and these paints are recommended for bathrooms and kitchen or where there's high humidity and steam.
Load flat or eggshell exterior paint color into paint sprayer. Depending on intensity of hue, apply one or two coats of flat or eggshell exterior paint to entire house. Be sure to work your way from top to bottom in a smooth, controlled manner, overlapping each stroke by 8 inches. TIP: When changing exterior color from light to dark or dark to light, start with a coat of primer to ensure proper coverage. Primer is not necessary when a fresh coat of existing color is being applied.
If the point of hiring a well established, experienced, reputable painting contractor is to secure the professionalism and trust suggested to be inherent with that choice, then I would EXPECT that professionalism and experience to include the ability to make the proper and correct calculations for labor and materials for a fixed price quote, and there should be NO reason for the contractor to put the cost burden of their miscalculation on the consumer.
The Lead Renovation, Repair and Painting (RRP) Rule establishes requirements for firms and individuals performing renovations, and affects contractors, property managers, and others who disturb painted surfaces.  It applies to work in houses, apartments, and child-occupied facilities (such as schools and day-care centers) built before 1978.  It includes pre-renovation education requirements as well as training, firm certification, and work practice requirements. 

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