Sharing a campaign that pulls from an ip?

Im making a dungeon crawl exploring the River of Death from the Garth Nix series "The Old Kingdom" Its based in an non descript city in a different world however im pulling the names of the gods from his books since im using their names to act as spells to get through the gates of death.

My question is two fold, one is this okay since I wish to share and make this free or should I avoid the proper noun thing entirely?

Second question is once I finish this is this a good place to post and share it, say through a google drive or something else, or is there a better location on reddit to say hey look, I made this thing, please enjoy?