'"Who is popular with the Donald and who isn't. Who's in, who's out, choosing who he can bully, that kinda thing.'"
Yes definitely because Trump needs people he can trust, not backstabbers. But Trump is incredible because he is a pragmatist and he can forgive attacks and slights just as easily as bullying the people who did it. If Trump thinks he can use someone then he will ignore ther slights, just as he ignored Rick Perry's or Mutt Romney's (who he used to humiliate and control) or Nikki Haley, but when Kelly Ayotte reportedly asked for a job in his Adinistration, he said no to her. So he chooses whether to ignore slights or not based on pure pragmatism, but also he looks for trust.
Trump will bully the Chinese over Taiwan etc, but in the end he will do a pragmatic deal that is to his and US advantage. It is not personal, it is business.
But some top people are hesistant to play the elite's Russian hacking game because they know that Trump may not play nice to them if he wins.
No one knows how ruthless Trump will be, but the elites know he will be if he wants to be.