2018 Chrysler Pacifica Parts and Specs for Install

Hi, I just bought a new 2018 Pacifica Touring Plus that I absolutely love. Hi, I just purchased a new 2018 Chrysler Pacifica Touring Plus. While the stock basic 6 speaker system actually sounds much better than I expected, I'd still like to improve on it a bit. I cannot find any information on exactly what components are used, their specifications, and how the speakers are all wired. Does anyone have any of that information to share? My plan is to just upgrade either just the four door speakers, or those plus the two dash corner speakers as well. I also have a self-powered sub-box I want to add. So all in all a pretty conservative upgrade, but one I know will bring a nice improvement to the system. I was looking on the Crutchfield site and found what they say are compatible speakers. The 6x9s I got to demo at a shop and would like to use are Kicker 3-ways (triaxles) listed by Crutchfield as only fitting in the rear doors. I assume this is the case due to the large magnet used on those speakers, which would block the windows from being able to roll down. I'm wondering if I could use a shim to bring the speakers outward enough to clear the window glass, but still fit underneath the stock grill panel? There is a different pair of 6x9s they say will fit the front doors, but those are listed as having an impedance of only 2.3 ohms, which concerns me. Because I don't know if that's how the stock system is already wired up and working or not. I don't want to connect too low of an impedance to it and cause damage to the head unit. I'm guessing that the two front door speakers and the small corner dash speakers are wired together in a way that raises the impedance to acceptable levels for the stock head unit. But I have no way of verifying that aside from pulling it all apart and going from there, which I really do not want to do. I don't have experience in car audio, and may need to hire an installer to help with this install, unless I can learn enough quickly to feel confident I can do it myself and get the right tools for the job. I'm assuming I'd have to pull the dash to access the rear of the head unit as well. I don't know if I can, how, or where I would connect the self-powered sub-box either. Any other tips or suggestions will be greatly appreciated!

Update per forum request: My vehicle uses a push to start ignition.