SAP PS & Project Server Integration

We are using ECC 6.0 and wish to integrate the SAP Project System and cProjects with Microsoft Project Server 2007. Our requirements of data exchange include the following:

When a new project is created in the SAP PS, the project's basic information and WBS structure should get pushed to Project Server and create a new project with the same WBS structure

When a resource is assigned to the project using cProject Resource Management, the same should get assigned to the project team in the Project Server

When a resource is released from a project using cProject Resource Management, the same should get released from the project team in the Project Server

At the end of the period (week or month), the summary of efforts entered in the Timesheet in Project Server should get posted to the SAP CATS or Project System tables

We would like to know which of the following (or any other tool) is the best way to achieve the above -

use of ERP Connector for Project Server 2007 provided by Microsoft

use of Open PS connector provided by SAP

use of either SAP XI or Microsoft BizTalk Server as the integration tool and writing custom code

Let me know the how you can provide consultancy to our team to achieve the above and what will be the charges?