Range Rover problems

Hello I have a range rover l322 2002 and I need to know the answers to my following problems-

the suspension on my car lowers it self and raises it self but I have a error message saying air suspension inactive and I cant manually lower or raise the car by myself.

Also there is a message saying check brake pads but I recently got them changed so why is it saying that?

next is the passenger door will not open and the rear door on the passenger side will not open from out side or when I lock or unlock the car it doesn't do any thing.