There is only one written for the Commercial, covers regulations, performance, weather, etc. And there are two for the CFI. To get a CFI, you must hold a Commercial and instrument rating in the category and class aircraft that you are applying for the CFI in. To get a Comm., you need 20 hours instruction, to get the IR, 15. You MIGHT be able to get those hours to overlap because the Comm. requires instrument instruction. I don't see a hour requirement for the CFI, just the spin endorsement. That being said, there are 7 aeras of operation that have to be signed off for the trainee and I can't see how they could be covered in under 10-12 hours.
FAR 61.41 allows the use of hours trained by a non-FAA CFI to count towards a FAA certificate, should just be a matter of making sure all the
aeras of operation are covered.
The requirements can be found here -
Electronic Code of Federal Regulations:
You should talk to the FAA, probably the airman certification branch in Oklahoma City.