Volkswagen and the Justice Department are nearing a deal to resolve criminal and civil allegations over the German automaker’s diesel cheating while it won long-awaited approval from the Environmental Protection Agency to fix about 70,000 diesel vehicles, crucial steps toward moving past a scandal that has cost it billions of dollars and its reputation. A successful settlement is critical to the automaker’s goal of rebuilding its business in the United States, a market key to its long-term growth plans and where VW brand sales were down 8 percent last year.