Yes, "1" is equal to approximately original KSP scale and "10" would be equal to RSS. I just set it to "2.5" by default to be a nice balance between realism and difficulty while still being able to use stock parts.
And yes, it increases the distance between bodies as well.
Sigma dimensions does a good job of scaling up the stock antennae ranges, so that is something neither of us have to worry about.
As for the Remotetech configs, I have included multiple preset configs for different scales, and you don't have to do anything with the files. All you have to do is select the correct config in the in-game Remotetech settings.
I don't really know what other Kopernicus mods would work with this mod. I would suspect that it would depend on the structure of the system. Mods that make modifications to the same files that this one does would probably have conflicts. I will try to add more integration for such mods in the future.
You do not have to do anything with the files in the compatibility folder. All of that should work automatically.
I have addressed that problem and I believe it has been fixed in the latest update. (1.0.3)