What exactly is the F/IC, an injector controller?
Fuel/Ignition Controller.
The F/IC is used to manage the installation of, typically, higher capacity fuel injectors. In operation, the Jeeps PCM no longer fires the injectors, it fires across a set of resistors in the F/IC. The F/IC uses this signal to control the physical injectors by looking in the FUEL table what it is you would like the injector to be doing.
At installation, the AEM F/IC wants to know what injectors were removed and what injectors were installed. By answering this one question, a basic fuel table is developed that brings the level of operation of the new injectors back to stock.
From this starting point, you adjust the fuel flow across the table based upon data from an Air Fuel Ratio gauge.
The "I" portion of F/IC is ignition retard. Primarily for boost applications, you must retard the spark under positive pressure to prevent detonation. Personally, I use hardware from Phormula for knock detection.
A side note here. The AEM F/IC gives you choices on how to program the fuel management, I use the "percent" mode as I find it the easiest to manage. Just read the error, do the math and apply the correction to the table.
I use the F/IC8 as it has additional features (speedometer correction and accelerator pump emulation) that the F/IC6 is lacking. Costs more though...
Hope this helped answer your question.