The engine was built at the same time the TBI system was added.
Forged pistons, 10:1 compression (I always run premium), Cam is a custom grind with Exh lift 444, Centerline 114, Duration 214, Intake Lift 443, Centerline 106, Duration 214, Cam timing is 105 degree intake, Rockers are OEM, Stock Cast iron intake with an adapter plate to attach the TBI unit.
ICM is a stock GM (currently an Autozone part), mounted to a heat sink with heat transfer paste (aluminum plate) mounted to the inner fender well away from heat and grounded well. Distance from ICM to coil by wire is probably three feet at max. The pickup wires from the distributor to the ICM have no shielding.
Os sensor is a 3-wire, heated unit, I have no idea what the brand is but told (by AFI) that if it needs to be replaced that a unit off of a 1995 Chevy K2500 w/ 350 will fit. The O2 sensor is mounted in a bung on the passenger side header collector.
Wiring harness custom built for the app by Affordable Fuel injection which supplied the whole kit and was supposed to custom burn the chip for the application.
I'm not sure about the ECM ground questions...I'm an electrician, I try to make sure everything is grounded to clean bare metal. The block and the body and frame are all bonded together well.
I have both ALDL and TunerPro software. I can record data easily with the ALDL software, but I haven't figured out the TunerPro software quite yet.
The injectors don't appear to leak.
The system did not come with a knock sensor, AFI knows it does not have a knock sensor and I assume they programmed the chip accordingly.
No idea if the EECM is a reman. I only know that it did not look new and I've swapped the EPROM several times with new burns from AFI.

I think that answers most of your questions...let me know if I missed anything.