RE: Is there a G2/G3 plane repository?
Any .plng3 files you download should go in the "Planes" directory where you installed RealFlight (example: C:\Program Files\RealFlight G3\Planes).
Any .tga or .dds should go in the "ColorSchemes" directory where you installed RealFlight (example: C:\Program Files\RealFlight G3\Colorschemes). If you don't have a "ColorSchemes" directory, you need to make one.