Carefully consider the gloss level. The shiny gloss paints are easy to clean, but will make any wall blemish stand out. The flat paints will help disguise wall blemishes, but can be difficult to clean. Generally, you'll want glossier paints where there's lots of steam or cooking (baths and kitchens) and in high-traffic areas. Flatter paints are preferred for large walls and ceilings.
Most of a projects price is the cost of labor at $25 to $75 per hour. However, most contractors bid out based on the entire project which includes all work hours. Hourly rates are only useful if your pro asks to do the job as “time and materials.” However, be wary of this pricing structure, it usually shows the contractor is uncertain how long the project will take.