hi gurus can you tell me about these

.>>We have standard info objects given in sap why you created zinfo objects can utell me the business scenario

>>

We have standard info cubes given in sap why you created zinfo cubes can utell me the business scenario

and

could u tell me this one also

.I have 2 Data Sources sales and Billing.I have 2 Cubes called 1.sales cube and 2.Billing Cube with its own Data,Now i want to add Sales Data to Billing Cube.How Can it Possible,Can you any one Explain?