Hard to know how Kasongo/Alexander will adapt, if they can rebound at near the same level as McGhee then I think you'll see what I posted. It those guys don't take to crashing the boards then you'll see McGhee get more minutes than I posted above. It's pretty obvious that they would prefer Kasongo/Alexander at the 5, those are the guys getting run there, it's up to them to keep their spots.
Reese is gonna be interesting to watch, Barnes has made it very clear to him that if he wants minutes on this team it's as a 4 who is willing to bang down low and fight for rebounds, to this point he's accepted that. If Reese starts floating around the outside and not banging down low he'll find himself out of the rotation quickly, it seems early on Barnes is hoping because of his potential 1-2 three pointers a game, and ability to run that he is hoping to have him in the rotation on an offense likely needing some firepower.
Agree with you on point guard, but I'm much happier to see that Punter is getting all the run there and they aren't attempting to play Armani there. Punter is gonna struggle to facilitate, but Barnes is a good enough coach that I don't think we will struggle against full court pressure like some may fear. It's why Barnes wants to run though, he wants the first open shot being taken if the ball can't be pushed to the rim or passed ahead on a fast break, he realizes they're likely gonna struggle in half court offensive sets with no real PG.