I can thoroughly recommend Lexus dealership in Swindon, very accommodating, helpful etc. I use them for my RC.
With regard to the rear door open/close button I think anything is possible but just how deep are your pockets? Was this ever an option for your model year? If yes then the parts are likely available but anything to do with Lexus retrofit is very costly.
Regarding the TPMS do you have wheel sensors fitted?