1. The SKT White Free theme contents will remain intact, the custom CSS, the theme options everything will remain as it is.
2. The moment you activate SKT White Pro all this won’t transfer as the white Pro had more parameters it wasn’t possible for us to keep it in the same location of the database and hence what you can do is copy the theme options content from free into Pro and unless your Pro is ready keep using the free.
So you can activate, check the old one. And then activate Pro and keep applying the settings.