Use of Cost Center Tariffs in cprojects Costing

[SAPuser7]

Dear PPM community,

we are using cprojects with task-based controlling and manual multilevel account assignment (WBS elements). Cprojects and SAP PS/CO run on two different systems.

Our requirement is to use role-specific cost rates in cprojects:
Role "Project Manager" gets cost rate "Project Manager".
Role "Engineer" gets cost rate "Engineer".

Further, each role should be assigned to exactly one cost center from SAP CO:
Role "Project Manager" is assigned to cost center "Project Management".
Role "Engineer" is assigned to cost center "Engineering".
The relationship role to cost center is 1:1.

Costing in cprojects should make use of CO cost center tariffs maintained in KP26. We want to avoid double maintenance of (actual) hourly rates in KP26 and (plan) hourly rates in PPM customizing. Actual and plan hourly rates are identical.

When transferring calculated costs to SAP PS, the cost center information from the assigned roles should be transferred to CO planning tables.

My questions are:

1. How to derive cost center from role? Am I correct to implement BAdIs DPR_FIN_GECCO_ATTR (in cprojects system) and IAOM_ATTRIBUTES (ATTRIBUTES_CPROJECTS) in S/4HANA system?
2. How to make use of KP26 cost center tariffs instead of maintaining PPM-specific cost rates? As per SAP Help Portal, it is possible to use "Plan price for the role in cost center accounting" to calculate costs for roles: Costing Logic | SAP Help Portal But how is it done?
3. How can we maintain the role-specific cost rates in a project template? Manual effort for operative project creation should be minimized.

Thank you so much for your input.
Best regards