DP001 - Is there a merit in calculating forecast accuracy for dollarized sales and decomposing it into Unit error and Price error?

There is every merit in tracking Forecast Accuracy in any organization. In fact, we will go on to say that the single most important metric in the entire organization is Sales Forecast accuracy. More.

DP002 - Why do you measure accuracy/error as forecast-actual / actual and not over forecast?

Historically Sales groups have been comfortable using forecast as a denominator, given their culture of beating their sales plan. Since most of the demand planning evolved from Sales function, MAPE was also measured this way. So this was mostly cultural. In such a scenario, Sales/Forecast will measure Sales attainment. For example, sales of 120 over 100 will mean a 120% attainment while the error of 20% will also be expressed as a proportion of their forecast. So it was more of a convenience for Sales Management. More.

DP003 - In calculating safety stock, you state that lead times are determined externally. Is the lead time given to you by the customer (which could vary enormously from customer to customer for the same SKU) or internal lead times for replenishment of inventory of the SKU?

Depending on where the safety stock policy is set, the lead-times are determined by the production or distribution process. For example, if Plant A takes three months to produce and ship a product to Distribution point XY, the lead time for safety stocks here is three months for setting inventory policy at Distribution Point XY. To be consistent, the safety stock at XY is based on the demand forecast error at this DC. This demand forecast error will be a function of the individual customer demand forecast errors at this DC. More.