@cwilliams563 I can't give a full answer to your question but might be able to shed some light.

You for sure want: Apple Carplay, SXM , backup, and a DVD (I don't know why you want a DVD player, but I'd suggest reassessing this as you could save a lot of money on a unit that doesn't have a dvd drive in it).

To accomplish all of those, any headunit (HU) (including the sony you're looking at) will accomplish that feat if it has those options (most head units will require an additional SXM receiver.. or you could play the SXM through your phone if you have the app and a subscription, saves about $85 on the receiver). To do those features you will not NEED the idatalink and Maestro, just the appropriate wiring harnesses. However If you have the JBL system though, the harness is not that much cheaper from the idatalink and Maestro setup and after experience I would just go with idatalink if you can afford it.

Now, I'm not sure about this but I'm speculating. Since you have a Kenwood unit installed already, you might be able get a newer Kenwood unit with Carplay, etc.. and hopefully just swap the HU and use the existing wiring harness already in place, Plug'n'Play theoretically. If this works, It'll be by far the easiest/cheapest route and I would do that.

Now if you do get a new HU and the idatalink and Maestro, I know some people have gotten those screens to display the info you want, but I'm unfamiliar with the specifics. I'd do research about the "Torque" app, as I believe thats what was used by the people who have done it. Remember though, just bc the HU and the idatalink can display that stuff, the car has to be able to provide that info to the HU.