Concourse C is clearly marked on AA's map of the JFK terminals and it is indeed the pier for 30s gates. I don't know the precise location but believe it is inside security (while the current 2 AC's are outside security). Opening date is Summer 2005 but MIA slipped by 6 months when it was within a month of opening; Christmas is more likely and almost no chance that it will be open by the July 4th weekend much less mid-June. Terminal map is at http://www.aa.com/content/travelInfo...tdetails.jhtml
Also see http://www.aa.com/content/urls/newYorkCity.jhtml