P3D v4 Airport Scenery - first questions - beginnings

Hello Guys, I want to start the adventure with creating airport scenery for P3Dv4, where to start, what programs do I need?
I would also like to convert airports from P3Dv3 to P3Dv4.
Can you direct me, what and how?
It depends on what you want to do. ADE will do most things for the airport itself, and a program like Blender or Sketchup will create the 3D buildings and other objects.
I would like to create small airports along with buildings on photosceneries and autogen. I also have a lot of small airports, compatible with fsx and p3dv3 and I would like to convert them to p3dv4. I care about the list of programs that are compatible with p3dv4 in which I'm good at doing it