From my experience, larger projects may include a "clearing & rough grading" package to be bid prior to construction. This serve a few purposes, including getting construction underway before plans are complete (obviously the site plan should be fairly refined, but the building plans are often not complete), getting a part of the contract done by a specialized contractor (therby avoiding the 10% the prime would tack on) and getting the much needed fill on site if needed ahead of time. The plan should mimick the final grading plan, but take into account planned pavement sections and building foundations. Utility should be considered if fill dramaitically increases elevation (especially if deep storm sewers are planned). As far as retaining walls, that most likely is a case by case situation. I would consider grading at slopes considered stabile for your soil type, depending on the impacts to the future construction phases.