I believe you can change the FSDO but that would best be a question for the FAA in Oklahoma City. Once you get the 61.75 PVT certificate based on your foreign license you will need a Flight Review which is a minimum of one hour of ground training and one hour of flight training before you can fly as PIC. Realistically I think it would be a few hours of ground training for a foreign pilot who has not flown in the US before the CFI would sign you off. That “based on” certificate will have all your current ratings. After that there really isn’t any “conversion.” You go through the same process as any regular US pilot. For your Commercial rating you’ll have to pass the Commercial written and a Commercial checkride for each category and class you want on your certificate. For your instrument to apply to your Commercial certificate you will have to pass the regular FAA instrument written and pass the instrument checkride. If you want the CFI there are two writtens and a checkride. If you want the Instrument Instructor rating there’s another written and another checkride. The ATP-CTP is class to fill the knowledge gap between a 1490 hour CFI and a 1530 hour regional jet pilot that is a requirement before you take the ATP Multi engine written. It does not prepare you for the ATM written. To get your type rating on anything other than your “based on” PVT you’ll have to go through a training center’s training program. It will be some ground school, some sim training and a checkride. The checkride has an oral examination and the maneuvers in appendix F to part 121. The oral is a couple hours of questions on the airplane systems.