SuperTed,
The J-1 visa is easy to get. Just find a school that can issue the visa, then you go to the U.S. Embassy and they add the visa to your passport. Word of warning the school issuing the J-1 will need the money for the course up front. The money up front meets the requirement by immigration to show you have enough money to complete your course and stay in the U.S.
To convert your J.A.A. license to an F.A.A. PPL based on your J.A.A. consists of going to the local F.A.A. office and showing them your license. They will issue you a U.S. PPL. To make the U.S. license current you will need to do a B.F.R. It will take about 3 hours total with an instructor (1.5 ground, 1.5 flight).
You do not need to do your I.R. but you will want to. It gives your F.A.A. CPL more privileges and you can get your instrument flight instructor rating, which makes it easier for you to find a job.
Good Luck,
Capt. Richard J. Gentil, Pres.
Naples Air Center, Inc.