It's not possible to customize main window and there is no other section in players list in the program. You can open popups on players by double-click on their nicknames and compare the stat values manually one-by-one. You can also use Range Research tool to explore pool tendencies.
Hand2Note doesn't calculate sample on expression stats by default. So if you want to see sample size for an expression stat in your HUD or popup, you need to create a separate expression stat for that.