Can you please guide me on Retroactive Billing configuration?

Retroactive Billing configuration:

1. What are the Mandatory configuration steps required for Retroactive Billing solution to work?

2. If I assign type 2 for Order Reason relevance for Retro-Billing of Credit/Debit Memos, it is not working.Any input on this is appreciated.

3. PDIF condition type, should it be placed in new Pricing procedure just after all Price condition types?

4. Will PDIF consider difference of Net price or Net value of the document?

5. Is Retroactive Billing applicable for Credit/Debit Memos against Return or Partial Return process?