HI, Audiovox installer here, and I've done a few Grand Cherokees too.
--The negative park lights can be had by tapping into the correct terminal, at the correct relay in the underhood fusebox, but I have never gone to that much trouble. (Same goes for the horn----that relay is under there too.)
--Go to the www.carsound.com forums and do a search on the Chrysler 300 or 300C. I believe my method of dealing with the resistor-based ignition wire is best.........with the other diagrams around, when you switch the key on after remote starting, the car's radio and climate controls go dead until after you hit the brake and kill the remote starter----harmless but annoying.
--You can probably just use the car's domelight wire as the door trigger, instead of diode-isolating the individual pinswitches------but you mustn't disable the domelight with the control on the turn signal lever, or then the alarm wouldn't go off if someone broke in.
--Go to bypasskit.com and see if they sell a piece that might make it easier to do the doorlocks. Even if they don't, I've rarely needed relays to do locks on a Chrysler product-----connect a pair of diodes (to block the positive pulses from the Audiovox unit) and fiddle around with different resistors until it works. (The wrong resistance won't blow anything up.)
--As far as dealing with the transponder in your key, you have a few choices:
A: Buy a universal key-in-the-box module like a DEI 555U or 556U, Audiovox AS-TCBM, or bypasskit.com TBK-III. You'll permanently LOSE one of the two keys that came with your Jeep----it goes inside the bypass box.
B. Get a DEI 556C or bypasskit.com PKU-CH2. It is basically a bypass box with a Chrysler transonder chip already inside------you program the chip to the car, and KEEP both your keys.
C. Get a universal key-in-the-box module, AND buy the correct blank Chrysler key from www.howardkeys.com, www.hlflake.com, or eBay. Plant the blank key in the box------you are doing the same thing as "B" above, except you're making it yourself out of two different pieces------as a pro, my cost is cheaper if I do it this way.
D: BEST CHOICE (in my opinion) Now that the 996A will be controlling everything, the factory Jeep remote control is just a nuisance......if you unlock the doors with it by mistake, it'll set the aftermarket alarm off.
If it were my car, I'd get a regular Chrysler key and program it to the car------whether you go do the dealer or a locksmith, or buy your own keyblank on eBay, pay a locksmith to cut it, and program it yourself. (Programming is easy; instructions are in your owner's manual.)
Now you have two of the factory Jeep remotes, and one plain key.
Plant the remote from one Jeep key in the bypass box and forget about it. Make the other Jeep key your spare. Attach the gray Chrsyler key to the Audiovox remote, and carry that around.