ABS - probably, if the V6 comes with similar sensors.
Immobilizer has to do with the ECU, so that depends on which route you go with that. If you use CL ecu, you also would need CL ignition and matching key. Otherwise, you would need to send out the ECU to have the immobilizer removed.
Can I tape a TL key to the TL ECU an use my original honda key and ignition or something, I've heard of that working but I am new to immobilizers, I'm gonna use the stock ecu until I need more power but for now the stock will work. So the immobilizer is actually part of the ECU? that's cool hahah
For the immobilizer, a remote start system bypass module is probably a better way to do it, since it can be tied to something like the key sense circuit which would then maintain the anti-theft functionality.
Of course a "key coffin" or the like it still a valid option.
A remote start system is basically a box that wires into your car, and lets you start the engine without actually going out to the car. If you live somewhere really cold (Like northern Canada) it's a very nice feature to have to allow your car to warm up before you go get into it. A bypass module for a remote starter is often less expensive than another key, though that depends on the manufacturer, and if they allow keys to be sold by people other than the dealerships. (If they're only available at the dealerships, they're usually more expensive.)
Since more and more cars come with immobilizer systems to keep people from hotwiring the car, and because essentially the remote start system wants to do more or less exactly that (hotwire the car, that is) they have bypass systems which allow the engine to start without the key in the ignition. Some of the older versions of these systems had a small box which holds a key with the transponder chip in it. These boxes got nicknamed "key coffins" because you had to give up one of your (usually expensive) keys and bury it somewhere difficult to locate inside the car.
Kind of beside the point, but remote start systems usually feature anti-theft features, making it impossible to move the car unless you actually put the key in the ignition, turning off if you press the brake, or clutch, or if you disengage the e-brake.
Thank you for going into detail, I've learned a lot. With the information you have given me, I will most likely get the key, ans matching ECU (including immobilizer system) and going that route. And maybe add remote start another time. I'm doing what I can to get the car started at this point. Im not sure what the immobilizer system does in a 2003 Acura TL, because at the moment I have no spark or fuel but it still turns the engine over.