This is one of the areas where the PT messed up. According to the PT, Qui-gon taught Yoda and Obi-wan how to be force ghosts. No one taught Anakin so how did he become a ghost? Luck? Genius? By virtue of being the Chosen One?
I hope they don’t mess with the Force Ghosts except as dispensers of wisdom, like Ben was in the OT.
And I was comparing the maturing Hayden to the younger pictures of Shaw and there is definitely a resemblance.