Interpreting OPF SP 1.2

While reading and then interpreting SP 1.2 of OPF "Appraise the Organization's Processes" it seems that it is a mini SCAMPI (correct me if I am wrong). Now in this context I have few questions and would like answered.

Organizational Process Focus (OPF) SP 1.2 states “Appraise the organization’s processes periodically and as needed to maintain an understanding of their strengths and weaknesses.”

1. These internal appraisals to satisfy this practice will be performed by the PEG (Process Engineering Group), how much rigor is required? Can we employ the SCAMPI Class C method to satisfy this practice?
SCAMPI A, B, and C appraisals all satisfy this practice as well as any other type of appraisals or assessments that provide an understanding of the organization’s process strengths and weaknesses. There is no level of rigor implied by this practice.

2. Should we check the evidences and/or satisfaction at processes' implementation at project level or its better to keep the scope of these appraisals at OU level only?
OPF is an organizational level process. And the practice states to appraise the organization’s processes. Some of them are performed at the project level and others at the organizational level. But the focus should be at the organizational level.

3. Should we formally present the findings as normally done in SCAMPI Class A appraisals by the LA or that much rigor is not required (as it required lot of stakeholders presence like CEO if he is the sponsor)?
The rigor of the Findings Presentation is up to you. However, you should determine the level of rigor when you are in the planning phase for these evaluations. As a Lead Appraiser, I create an appraisal plan for any appraisal I conduct and I specify in the plan how the practices, projects, organization, etc. will be scored and how the results will be presented.

4. If we are appraising the organizational processes, then should we appraise all the ML 2 and ML 3 process area or we can make selection?
Since this practice covers all process appraisals conducted on the organization’s processes, depending on the appraisal, you have a lot of flexibility on the scope and conduct. It all needs to be specified in the appraisal plan. Of course a SCAMPI A appraisal using the staged representation will dictate which PAs to include depending on the Maturity Level. Other than the SCAMPI A, you have the freedom to pick and choose what you want to appraise. But keep in mind, you do need to have an overall strategy and plan for these appraisals. As a Lead Appraiser appraising this practice, I expect to see a periodic plan for your appraisals, not just the SCAMPI A appraisals I conducted.

5. If we make a checklist for all process areas, then is it a good idea that we include the Subpractices as a questions (may be not all subpractices) in checklist for all ML 2 and ML 3 PAs?
Again, you can use whatever checklists you want for your internal appraisals. In fact, it might work to your advantage to be very rigorous in an internal appraisal. But remember, when it comes time for the SCAMPI A appraisal, you will not be evaluated against the sub-practices.