Ls4302b

Hey everyone!
I am picking up my 2005 Lexus LS430 Ultra Luxury model. Flint Mica, black leather guts and 151K on the clock. I plan on doing the following mods/maintence within the next few weeks:

-Timing Belt replacement
-Oil change, fluids topped off

-Looking at either doing the Datasystems controller (model# ASC680) and wiring harness(H-087D ASR681/ASC680) Correct me if I am wrong
-Tint
-Kranze Bazeria 19x9 & 19x10 wheels or Ordens. I would prefer 20's but am still looking around for something perfect.

I am looking on this website but if anyone can chime in to help with the research.I was wondering the following;

-If I ran the controller for the OEM airbags to go slightly lower then all the way down when I park, how is the wear and tear life going to be? Should I switch out the suspension for an aftermarket airbag setup up or switch to coilovers? Will I be okay with the controller and factory airbags.

-Audio question, factory NAV is outdated so I am looking to get a new double din TV/apple car play head unit and saw that you can still retain the oem nav screen and functions. Any pros/cons from anyone who knows or has experience with this? Can I retain the rear controls for the radio in the backseat armrest?

Thanks and I look forward to learn more about this "new to me" Lexus.