The 'Lighter' Side Of The Force
Jedi get light side ghosts. And in previous stories. Non canon now former sith lords have had spirits ands ghosts interact with people. Could be it is vader as a dark side ghost. Would explain his knowledge of vader turning to the light. And the feeling he felt that took him there. Would also explain how he would be able to turn kylo Ren
Luke trained Ben Solo prior to his turning to the dark side and becoming Kylo Ren. It's more likely that Luke told him stories about Vader's redemption and THAT is how Kylo learned about it all.
I think den Palpatin is Snoke
i think that al gore is snoke and that he called him self snoke after killing manbearpig