1 - The AFCAD included with the scenery is the last and most updated one. We always keep the full installer updated
2 - Of course they work
3 - The plateau effect created by 3rd party meshes, can be fixed with the file that is available here in another post. This is the only file you need to add, otherwise there's nothing to touch after the installation, using the current installer.
But of course, the real reply is:
Why don't you simply TRY the scenery yourself, before buying ?