From what I saw from their website you will need to do some complex-looking stuff to have your module compatible with it, so how compatible is it with the singleplayer? Is there an easy way to uninstall it if I want to play an incompatible module? The manual was made before the old vault was taken down, are the CEP merge instructions still valid? Now that I think about it, is CEP even compatible with everything? I only installed it because it was on a guide on how to get the latest patches on NWN.

You don't have any need to uninstall for the sake fo incompatible modules.

Once the files are installed, you then run the PRC Module Updater (from the install directory, not the desktop; usually won't matter, but desktop shortcut doesn't include the prc_ocfix that the original campaign needs) to add it to a module. You choose which modules to apply it to, so if you're playing one that's not compatible, just don't install it to that one.

It also applies reasonably well to a decent number of other modules. I remember Ronin working well ages ago, and I think Siege of Shadowdale also worked, though it's been so long that I can't think of any others.

Can't help with the CEP stuff, though.