Oh answering the original question.
FAR book and part 61 explains all the requirments, both practical and theoretical, to obtain a FAA CPL with Instrument rating. Also same pt 61 explains what you need to get credit from your exsisting licence towards FAA licences.
A good way is to consult a coule of schools in US and compare their answers. Try to find someone who has worked in US as CFI and has experience on this type of matters.
JJ