As far as I recall there is a special 50 question knowledge test to convert the IR, not sure another flight test is required for the IR. For the Commercial there is another knowledge test of 100 questions in 3 hours. You should be able to do the SE/ME Commercial with about 20 hours of training.
you will need to get a visa and TSA approval. This means using a flight school with immigration status. Your best best here is to contact the many Florida based schools that advertise here on Pprune and ask them for the full SP.
Its will surprise you at how much simpler it is.