Please find the attached for SAP C4C integration with SAP ERP, I think you can use this documents to discuss with the implementer which they should suggest best practice solution for us.
I have made an appointment for IT management to present the solution which you will be implemented on Wednesday. Please you preparing for presentation slide which are included list of solution, scope of work, compare solution matrix between on Cloud vs on premise, Pros & Cons, Project timeline, and SAP interfacing. I hope that this slide will help the management can decision making go to the project.