What specifically should I be looking for? Are there any COR audit checklist available anywhere?
You shouldn't be looking for checklists. You are not an auditor. You can only comment on what you see and know and understand. If a contracting officer really needs an auditor to review the contractors billing system, then he/she must contact DCAA. You are not trained, nor authorized to do that job. The contracting officer can not delegate auditing responsiblities to you!
Open full Question Details
Using CLINs to funds services not intented for that CLIN: You should comment on whether you believe the contractor is doing the work described in the contract line item and Statement of Work. If the job is to hang curtains, have you observed them hanging curtains? If their job is to do aircraft maintenance. Are they doing this job? If you have a QASP, you should check that they are in compliance with the tasks and metrics laid out in this plan.
Abuse of ODC's: I think this would require the review of the contractor billing system. It needs to be done by an auditor.
Go back and talk to your Contracting Officer. Find out exactly what they need you to do. If you feel uncomfortable, then say so. Show them this AAP. You cannot go into the contractors books and audit.