The Dark Side of the Force is a pathway to many abilities some consider to be unnatural. They literally quoted Palpatine from Revenge of the Sith.
Rey was the daughter of his clone. His clone had no force powers and was a disappointment.
how he was able to transfer his soul into another dying clone, and maintain his midichlorians they never explain.
there is no way his body survived the death stars explosion or falling into a reactor. It’s absurd even for Star Wars.