JusticeForGP2

I am VERY confused about the installation instructions. I want to install the retro shuttle, and have all dependencies up to date and installed, so do I delete "Modern_Shuttle_IVA.cfg", put "USIVA_FullRetro.cfg" directly into my GameData folder, or into the ultimate shuttle iva folder INSIDE my GameData folder? Or is there something else I need to do? I have tried G'th's instructions and leoli6's instructions to no avail. Please help.

I know it has already been asked two years ago, but will Kerbol Origins work with OPM and Extrasolar?