Campaign and Purchase Requisition Integration

Hi

Want to understand on the following points:

1. In CRM a Campaign is created and released it. Purchase Requirement details have been entered(like Purchase Goods/service, plant and Estimated cost price) in it and PR # is automatically created once the Campaign is saved.

Any one explain how the PR number(and also PO number as followup document created in ECC) gets updated in CRM along with the PO status from ECC.

2. Once the PR is created in ECC , if some one changes the Estimated cost price of line item in PR (in ECC system) will this get updated back to CRM or not. If yes how:  and if not why?

Regards

Vijay