James, 'Iguanas are pretty much stationary so no need to lead them for the shot.
Rifle of choice is usually a PCP air rifle about 22+ caliber supressed. These hunts are pretty much in populated areas.
As far as I know,no hunting license is needed down in FL for Iguanas but I think the proper proceedure is to call the loacal PD to let them know what area you will be in.